Avoid errors with buggy preprocessors

extra/config/lkc_proto.h

@@ -5,7 +5,7 @@ P(conf_read,int,(const char *name));
 P(conf_write,int,(const char *name));
 
 /* menu.c */
-P(rootmenu,struct menu,);
+extern struct menu rootmenu;
 
 P(menu_is_visible,bool,(struct menu *menu));
 P(menu_get_prompt,const char *,(struct menu *menu));
@@ -14,7 +14,7 @@ P(menu_get_parent_menu,struct menu *,(struct menu *menu));
 
 /* symbol.c */
 P(symbol_hash,struct symbol *,[SYMBOL_HASHSIZE]);
-P(sym_change_count,int,);
+extern int sym_change_count;
 
 P(sym_lookup,struct symbol *,(const char *name, int isconst));
 P(sym_find,struct symbol *,(const char *name));