Store warnings and errors in a parser state infolog.

Cleans up compile warning about unused state in _mesa_glsl_warning.  We
would want infolog handling roughly like this anyway.
diff --git a/glsl_parser_extras.h b/glsl_parser_extras.h
index 125c675..b06b3fe 100644
--- a/glsl_parser_extras.h
+++ b/glsl_parser_extras.h
@@ -65,6 +65,8 @@
    const glsl_type **user_structures;
    unsigned num_user_structures;
 
+   char *info_log;
+
    /**
     * \name Enable bits for GLSL extensions
     */
@@ -95,7 +97,7 @@
  * \sa _mesa_glsl_error
  */
 extern void _mesa_glsl_warning(const YYLTYPE *locp,
-			       const _mesa_glsl_parse_state *state,
+			       _mesa_glsl_parse_state *state,
 			       const char *fmt, ...);
 
 extern void _mesa_glsl_lexer_ctor(struct _mesa_glsl_parse_state *state,