diff --git a/Makefile.in b/Makefile.in
index 18456383..641226a0 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -2185,12 +2185,10 @@ DEPDIR = @DEPDIR@
 ECHO_C = @ECHO_C@
 ECHO_N = @ECHO_N@
 ECHO_T = @ECHO_T@
-EGREP = @EGREP@
 ETAGS = @ETAGS@
 EXEEXT = @EXEEXT@
 GMOCK_CFLAGS = @GMOCK_CFLAGS@
 GMOCK_LIBS = @GMOCK_LIBS@
-GREP = @GREP@
 GTEST_CFLAGS = @GTEST_CFLAGS@
 GTEST_LIBS = @GTEST_LIBS@
 HAVE_CXX17 = @HAVE_CXX17@
diff --git a/aclocal.m4 b/aclocal.m4
index 009cc48e..31be0bad 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -848,35 +848,6 @@ else
 fi
 ])
 
-#  -*- Autoconf -*-
-# Obsolete and "removed" macros, that must however still report explicit
-# error messages when used, to smooth transition.
-#
-# Copyright (C) 1996-2021 Free Software Foundation, Inc.
-#
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
-AC_DEFUN([AM_CONFIG_HEADER],
-[AC_DIAGNOSE([obsolete],
-['$0': this macro is obsolete.
-You should use the 'AC][_CONFIG_HEADERS' macro instead.])dnl
-AC_CONFIG_HEADERS($@)])
-
-AC_DEFUN([AM_PROG_CC_STDC],
-[AC_PROG_CC
-am_cv_prog_cc_stdc=$ac_cv_prog_cc_stdc
-AC_DIAGNOSE([obsolete],
-['$0': this macro is obsolete.
-You should simply use the 'AC][_PROG_CC' macro instead.
-Also, your code should no longer depend upon 'am_cv_prog_cc_stdc',
-but upon 'ac_cv_prog_cc_stdc'.])])
-
-AC_DEFUN([AM_C_PROTOTYPES],
-         [AC_FATAL([automatic de-ANSI-fication support has been removed])])
-AU_DEFUN([fp_C_PROTOTYPES], [AM_C_PROTOTYPES])
-
 # Helper functions for option handling.                     -*- Autoconf -*-
 
 # Copyright (C) 2001-2021 Free Software Foundation, Inc.
diff --git a/configure b/configure
index 76d4a9f6..fb84fb0d 100755
--- a/configure
+++ b/configure
@@ -182,8 +182,7 @@ test -x / || exit 1"
   as_suggested="  as_lineno_1=";as_suggested=$as_suggested$LINENO;as_suggested=$as_suggested" as_lineno_1a=\$LINENO
   as_lineno_2=";as_suggested=$as_suggested$LINENO;as_suggested=$as_suggested" as_lineno_2a=\$LINENO
   eval 'test \"x\$as_lineno_1'\$as_run'\" != \"x\$as_lineno_2'\$as_run'\" &&
-  test \"x\`expr \$as_lineno_1'\$as_run' + 1\`\" = \"x\$as_lineno_2'\$as_run'\"' || exit 1
-test \$(( 1 + 1 )) = 2 || exit 1"
+  test \"x\`expr \$as_lineno_1'\$as_run' + 1\`\" = \"x\$as_lineno_2'\$as_run'\"' || exit 1"
   if (eval "$as_required") 2>/dev/null
 then :
   as_have_required=yes
@@ -685,8 +684,6 @@ PTHREAD_CFLAGS
 PTHREAD_LIBS
 PTHREAD_CC
 ax_pthread_config
-EGREP
-GREP
 RANLIB
 am__fastdepCXX_FALSE
 am__fastdepCXX_TRUE
@@ -1719,39 +1716,6 @@ fi
 
 } # ac_fn_cxx_try_compile
 
-# ac_fn_c_check_header_compile LINENO HEADER VAR INCLUDES
-# -------------------------------------------------------
-# Tests whether HEADER exists and can be compiled using the include files in
-# INCLUDES, setting the cache variable VAR accordingly.
-ac_fn_c_check_header_compile ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
-printf %s "checking for $2... " >&6; }
-if eval test \${$3+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$4
-#include <$2>
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"
-then :
-  eval "$3=yes"
-else $as_nop
-  eval "$3=no"
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-eval ac_res=\$$3
-	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-printf "%s\n" "$ac_res" >&6; }
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-
-} # ac_fn_c_check_header_compile
-
 # ac_fn_c_try_link LINENO
 # -----------------------
 # Try to link conftest.$ac_ext, and return whether this succeeded.
@@ -1799,6 +1763,39 @@ fi
 
 } # ac_fn_c_try_link
 
+# ac_fn_c_check_header_compile LINENO HEADER VAR INCLUDES
+# -------------------------------------------------------
+# Tests whether HEADER exists and can be compiled using the include files in
+# INCLUDES, setting the cache variable VAR accordingly.
+ac_fn_c_check_header_compile ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
+printf %s "checking for $2... " >&6; }
+if eval test \${$3+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+$4
+#include <$2>
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+  eval "$3=yes"
+else $as_nop
+  eval "$3=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+eval ac_res=\$$3
+	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+printf "%s\n" "$ac_res" >&6; }
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+
+} # ac_fn_c_check_header_compile
+
 # ac_fn_c_check_func LINENO FUNC VAR
 # ----------------------------------
 # Tests whether FUNC exists, setting the cache variable VAR accordingly
@@ -6937,180 +6934,6 @@ if test "x$enable_m32" = xyes; then
   CXXFLAGS="${CXXFLAGS} -m32"
 fi
 
-# Autoupdate added the next two lines to ensure that your configure
-# script's behavior did not change.  They are probably safe to remove.
-ac_header= ac_cache=
-for ac_item in $ac_header_c_list
-do
-  if test $ac_cache; then
-    ac_fn_c_check_header_compile "$LINENO" $ac_header ac_cv_header_$ac_cache "$ac_includes_default"
-    if eval test \"x\$ac_cv_header_$ac_cache\" = xyes; then
-      printf "%s\n" "#define $ac_item 1" >> confdefs.h
-    fi
-    ac_header= ac_cache=
-  elif test $ac_header; then
-    ac_cache=$ac_item
-  else
-    ac_header=$ac_item
-  fi
-done
-
-
-
-
-
-
-
-
-if test $ac_cv_header_stdlib_h = yes && test $ac_cv_header_string_h = yes
-then :
-
-printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
-
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for grep that handles long lines and -e" >&5
-printf %s "checking for grep that handles long lines and -e... " >&6; }
-if test ${ac_cv_path_GREP+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test -z "$GREP"; then
-  ac_path_GREP_found=false
-  # Loop through the user's path and test for each of PROGNAME-LIST
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_prog in grep ggrep
-   do
-    for ac_exec_ext in '' $ac_executable_extensions; do
-      ac_path_GREP="$as_dir$ac_prog$ac_exec_ext"
-      as_fn_executable_p "$ac_path_GREP" || continue
-# Check for GNU ac_path_GREP and select it if it is found.
-  # Check for GNU $ac_path_GREP
-case `"$ac_path_GREP" --version 2>&1` in
-*GNU*)
-  ac_cv_path_GREP="$ac_path_GREP" ac_path_GREP_found=:;;
-*)
-  ac_count=0
-  printf %s 0123456789 >"conftest.in"
-  while :
-  do
-    cat "conftest.in" "conftest.in" >"conftest.tmp"
-    mv "conftest.tmp" "conftest.in"
-    cp "conftest.in" "conftest.nl"
-    printf "%s\n" 'GREP' >> "conftest.nl"
-    "$ac_path_GREP" -e 'GREP$' -e '-(cannot match)-' < "conftest.nl" >"conftest.out" 2>/dev/null || break
-    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
-    as_fn_arith $ac_count + 1 && ac_count=$as_val
-    if test $ac_count -gt ${ac_path_GREP_max-0}; then
-      # Best one so far, save it but keep looking for a better one
-      ac_cv_path_GREP="$ac_path_GREP"
-      ac_path_GREP_max=$ac_count
-    fi
-    # 10*(2^10) chars as input seems more than enough
-    test $ac_count -gt 10 && break
-  done
-  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
-esac
-
-      $ac_path_GREP_found && break 3
-    done
-  done
-  done
-IFS=$as_save_IFS
-  if test -z "$ac_cv_path_GREP"; then
-    as_fn_error $? "no acceptable grep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
-  fi
-else
-  ac_cv_path_GREP=$GREP
-fi
-
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_GREP" >&5
-printf "%s\n" "$ac_cv_path_GREP" >&6; }
- GREP="$ac_cv_path_GREP"
-
-
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for egrep" >&5
-printf %s "checking for egrep... " >&6; }
-if test ${ac_cv_path_EGREP+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if echo a | $GREP -E '(a|b)' >/dev/null 2>&1
-   then ac_cv_path_EGREP="$GREP -E"
-   else
-     if test -z "$EGREP"; then
-  ac_path_EGREP_found=false
-  # Loop through the user's path and test for each of PROGNAME-LIST
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH$PATH_SEPARATOR/usr/xpg4/bin
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_prog in egrep
-   do
-    for ac_exec_ext in '' $ac_executable_extensions; do
-      ac_path_EGREP="$as_dir$ac_prog$ac_exec_ext"
-      as_fn_executable_p "$ac_path_EGREP" || continue
-# Check for GNU ac_path_EGREP and select it if it is found.
-  # Check for GNU $ac_path_EGREP
-case `"$ac_path_EGREP" --version 2>&1` in
-*GNU*)
-  ac_cv_path_EGREP="$ac_path_EGREP" ac_path_EGREP_found=:;;
-*)
-  ac_count=0
-  printf %s 0123456789 >"conftest.in"
-  while :
-  do
-    cat "conftest.in" "conftest.in" >"conftest.tmp"
-    mv "conftest.tmp" "conftest.in"
-    cp "conftest.in" "conftest.nl"
-    printf "%s\n" 'EGREP' >> "conftest.nl"
-    "$ac_path_EGREP" 'EGREP$' < "conftest.nl" >"conftest.out" 2>/dev/null || break
-    diff "conftest.out" "conftest.nl" >/dev/null 2>&1 || break
-    as_fn_arith $ac_count + 1 && ac_count=$as_val
-    if test $ac_count -gt ${ac_path_EGREP_max-0}; then
-      # Best one so far, save it but keep looking for a better one
-      ac_cv_path_EGREP="$ac_path_EGREP"
-      ac_path_EGREP_max=$ac_count
-    fi
-    # 10*(2^10) chars as input seems more than enough
-    test $ac_count -gt 10 && break
-  done
-  rm -f conftest.in conftest.tmp conftest.nl conftest.out;;
-esac
-
-      $ac_path_EGREP_found && break 3
-    done
-  done
-  done
-IFS=$as_save_IFS
-  if test -z "$ac_cv_path_EGREP"; then
-    as_fn_error $? "no acceptable egrep could be found in $PATH$PATH_SEPARATOR/usr/xpg4/bin" "$LINENO" 5
-  fi
-else
-  ac_cv_path_EGREP=$EGREP
-fi
-
-   fi
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_path_EGREP" >&5
-printf "%s\n" "$ac_cv_path_EGREP" >&6; }
- EGREP="$ac_cv_path_EGREP"
-
-
-
 # Check whether --enable-largefile was given.
 if test ${enable_largefile+y}
 then :
@@ -7678,6 +7501,35 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+ac_header= ac_cache=
+for ac_item in $ac_header_c_list
+do
+  if test $ac_cache; then
+    ac_fn_c_check_header_compile "$LINENO" $ac_header ac_cv_header_$ac_cache "$ac_includes_default"
+    if eval test \"x\$ac_cv_header_$ac_cache\" = xyes; then
+      printf "%s\n" "#define $ac_item 1" >> confdefs.h
+    fi
+    ac_header= ac_cache=
+  elif test $ac_header; then
+    ac_cache=$ac_item
+  else
+    ac_header=$ac_item
+  fi
+done
+
+
+
+
+
+
+
+
+if test $ac_cv_header_stdlib_h = yes && test $ac_cv_header_string_h = yes
+then :
+
+printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
+
+fi
 ac_fn_c_check_header_compile "$LINENO" "a.out.h" "ac_cv_header_a_out_h" "$ac_includes_default"
 if test "x$ac_cv_header_a_out_h" = xyes
 then :
@@ -10767,6 +10619,7 @@ DEFS=-DHAVE_CONFIG_H
 
 ac_libobjs=
 ac_ltlibobjs=
+U=
 for ac_i in : $LIBOBJS; do test "x$ac_i" = x: && continue
   # 1. Remove the extension, and $U if already installed.
   ac_script='s/\$U\././;s/\.o$//;s/\.obj$//'
diff --git a/configure.ac b/configure.ac
index ca293669..1d53bc61 100644
--- a/configure.ac
+++ b/configure.ac
@@ -37,7 +37,7 @@ AC_CONFIG_MACRO_DIR([m4])
 AC_CANONICAL_HOST
 
 AM_INIT_AUTOMAKE(subdir-objects tar-ustar 1.13)
-AM_CONFIG_HEADER(src/config.h)
+AC_CONFIG_HEADERS(src/config.h)
 AM_MAINTAINER_MODE
 
 AM_PROG_AR
@@ -59,15 +59,6 @@ if test "x$enable_m32" = xyes; then
   CXXFLAGS="${CXXFLAGS} -m32"
 fi
 
-m4_warn([obsolete],
-[The preprocessor macro `STDC_HEADERS' is obsolete.
-  Except in unusual embedded environments, you can safely include all
-  ISO C90 headers unconditionally.])dnl
-# Autoupdate added the next two lines to ensure that your configure
-# script's behavior did not change.  They are probably safe to remove.
-AC_CHECK_INCLUDES_DEFAULT
-AC_PROG_EGREP
-
 AC_SYS_LARGEFILE
 AX_PTHREAD
 AC_CHECK_HEADERS([a.out.h sys/mman.h sys/random.h])