autoconf.el fix to support AS_HELP_STRING etc

[Simon Josefsson]

Recent Autoconf releases include macros that begin with AS_, such as
AS_HELP_STRING.  I've committed this patch to make the autoconf font
locking code recognize them.

--- autoconf.el 10 Apr 2004 20:02:45 +0200      1.7
+++ autoconf.el 30 Oct 2004 01:28:58 +0200      
@@ -1,6 +1,6 @@
 ;;; autoconf.el --- mode for editing Autoconf configure.in files
 
-;; Copyright (C) 2000, 2003 Free Software Foundation, Inc.
+;; Copyright (C) 2000, 2003, 2004 Free Software Foundation, Inc.
 
 ;; Author: Dave Love <address@hidden>
 ;; Keywords: languages
@@ -49,7 +49,7 @@
   "AC_\\(SUBST\\|DEFINE\\(_UNQUOTED\\)?\\)(\\(\\sw+\\)")
 
 (defvar autoconf-font-lock-keywords
-  `(("A[CHM]_\\sw+" . font-lock-keyword-face)
+  `(("A[CHMS]_\\sw+" . font-lock-keyword-face)
     (,autoconf-definition-regexp
      3 font-lock-function-name-face)
     ;; Are any other M4 keywords really appropriate for configure.in,