fix implicit declaration compilation warning.

--- tools/lemon.c.orig	Sun Dec 12 10:16:41 2010
+++ tools/lemon.c	Sun Dec 12 10:16:53 2010
@@ -2985,6 +2985,7 @@ struct lemon *lemp;
   FILE *in;
   char *tpltname;
   char *cp;
+  extern int access();
 
   cp = strrchr(lemp->filename,'.');
   if( cp ){