Merge changes from gnulib. This was prompted because the CVS

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

m4/alloca.m4

@@ -0,0 +1,36 @@
+# alloca.m4 serial 2
+dnl Copyright (C) 2002-2003 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.
+
+AC_DEFUN([gl_FUNC_ALLOCA],
+[
+  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
+  AC_REQUIRE([AC_PROG_CPP])
+  AC_REQUIRE([AC_PROG_EGREP])
+
+  AC_REQUIRE([AC_FUNC_ALLOCA])
+  if test $ac_cv_func_alloca_works = no; then
+    gl_PREREQ_ALLOCA
+  fi
+
+  # Define an additional variable used in the Makefile substitution.
+
+  AC_EGREP_CPP([Need own alloca], [
+#if defined __GNUC__ || defined _MSC_VER || !HAVE_ALLOCA_H
+  Need own alloca
+#endif
+    ],
+    ALLOCA_H=alloca.h,
+    ALLOCA_H=)
+  AC_SUBST([ALLOCA_H])
+])
+
+# Prerequisites of lib/alloca.c.
+# STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
+AC_DEFUN([gl_PREREQ_ALLOCA], [
+  AC_CHECK_HEADERS_ONCE(stdlib.h string.h)
+])