Merge changes from gnulib. This was prompted because the CVS

snapshot of Bison didn't build on Solaris 7 due to strnlen problems.

m4/realloc.m4

@@ -0,0 +1,25 @@
+# realloc.m4 serial 7
+dnl Copyright (C) 2002 Free Software Foundation, Inc.
+dnl This file is free software, distributed under the terms of the GNU
+dnl General Public License.  As a special exception to the GNU General
+dnl Public License, this file may be distributed as part of a program
+dnl that contains a configuration script generated by Autoconf, under
+dnl the same distribution terms as the rest of that program.
+
+dnl From Jim Meyering.
+dnl Determine whether realloc works when both arguments are 0.
+dnl If it doesn't, arrange to use the replacement function.
+
+AC_DEFUN([jm_FUNC_REALLOC],
+[
+  AC_REQUIRE([AC_FUNC_REALLOC])
+  dnl autoconf < 2.57 used the symbol ac_cv_func_realloc_works.
+  if test X"$ac_cv_func_realloc_0_nonnull" = Xno || test X"$ac_cv_func_realloc_works" = Xno; then
+    gl_PREREQ_REALLOC
+  fi
+])
+
+# Prerequisites of lib/realloc.c.
+AC_DEFUN([gl_PREREQ_REALLOC], [
+  :
+])