+m4_version_prereq([2.70], [] ,[
+
+# This is taken from the following Autoconf patch:
+# http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
+AC_DEFUN([_AC_FUNC_REALLOC_IF],
+[
+ AC_REQUIRE([AC_HEADER_STDC])dnl
+ AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+ AC_CHECK_HEADERS([stdlib.h])
+ AC_CACHE_CHECK([for GNU libc compatible realloc],
+ [ac_cv_func_realloc_0_nonnull],
+ [AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#if defined STDC_HEADERS || defined HAVE_STDLIB_H
+ # include <stdlib.h>
+ #else
+ char *realloc ();
+ #endif
+ ]],
+ [[return ! realloc (0, 0);]])
+ ],
+ [ac_cv_func_realloc_0_nonnull=yes],
+ [ac_cv_func_realloc_0_nonnull=no],
+ [case "$host_os" in
+ # Guess yes on platforms where we know the result.
+ *-gnu* | freebsd* | netbsd* | openbsd* \
+ | hpux* | solaris* | cygwin* | mingw*)
+ ac_cv_func_realloc_0_nonnull=yes ;;
+ # If we don't know, assume the worst.
+ *) ac_cv_func_realloc_0_nonnull=no ;;
+ esac
+ ])
+ ])
+ AS_IF([test $ac_cv_func_realloc_0_nonnull = yes], [$1], [$2])
+])# AC_FUNC_REALLOC
+
+])
+