Merge changes from gnulib. This was prompted because the CVS

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

m4/stdbool.m4

@@ -1,6 +1,6 @@
 # Check for stdbool.h that conforms to C99.
 
-# Copyright (C) 2002 Free Software Foundation, Inc.
+# Copyright (C) 2002-2003 Free Software Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -17,6 +17,32 @@
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 # 02111-1307, USA.
 
+# Prepare for substituting <stdbool.h> if it is not supported.
+
+AC_DEFUN([AM_STDBOOL_H],
+[
+  AC_REQUIRE([AC_HEADER_STDBOOL])
+
+  # Define two additional variables used in the Makefile substitution.
+
+  if test "$ac_cv_header_stdbool_h" = yes; then
+    STDBOOL_H=''
+  else
+    STDBOOL_H='stdbool.h'
+  fi
+  AC_SUBST([STDBOOL_H])
+
+  if test "$ac_cv_type__Bool" = yes; then
+    HAVE__BOOL=1
+  else
+    HAVE__BOOL=0
+  fi
+  AC_SUBST([HAVE__BOOL])
+])
+
+# This macro is only needed in autoconf <= 2.54.  Newer versions of autoconf
+# have this macro built-in.
+
 AC_DEFUN([AC_HEADER_STDBOOL],
   [AC_CACHE_CHECK([for stdbool.h that conforms to C99],
      [ac_cv_header_stdbool_h],
@@ -57,6 +83,7 @@ AC_DEFUN([AC_HEADER_STDBOOL],
 	[ return !a + !b + !c + !d + !e + !f + !g + !h + !i; ],
 	[ac_cv_header_stdbool_h=yes],
 	[ac_cv_header_stdbool_h=no])])
+   AC_CHECK_TYPES([_Bool])
    if test $ac_cv_header_stdbool_h = yes; then
      AC_DEFINE(HAVE_STDBOOL_H, 1, [Define to 1 if stdbool.h conforms to C99.])
    fi])