Fix mp_frozen_names

Author: tannewt

py/builtinhelp.c

@@ -77,14 +77,17 @@ STATIC void mp_help_add_from_names(mp_obj_t list, const char *name) {
 }
 #endif
 
+#if MICROPY_MODULE_FROZEN
+extern const char mp_frozen_names[];
+#endif
+
 STATIC void mp_help_print_modules(void) {
     mp_obj_t list = mp_obj_new_list(0, NULL);
 
     mp_help_add_from_map(list, &mp_builtin_module_map);
     mp_help_add_from_map(list, &mp_builtin_extensible_module_map);
 
     #if MICROPY_MODULE_FROZEN
-    extern const char mp_frozen_names[];
     mp_help_add_from_names(list, mp_frozen_names);
     #endif