Use normal parser for menu entries.

Reported by: Thomas Frauendorfer

	* include/grub/parser.h (grub_parser_execute): Don't export.
	* normal/menu.c (grub_menu_execute_entry_real): New function.
	(grub_menu_execute_entry): Use grub_menu_execute_entry_real.

include/grub/parser.h

@@ -83,7 +83,7 @@ struct grub_parser
 };
 typedef struct grub_parser *grub_parser_t;
 
-grub_err_t EXPORT_FUNC(grub_parser_execute) (char *source);
+grub_err_t grub_parser_execute (char *source);
 
 grub_err_t
 grub_rescue_parse_line (char *line, grub_reader_getline_t getline);