Fix #3969: Custom currency's gets reset when closing the game

Custom currency loading code was being called from a not usually reached
place.

src/config.c

@@ -476,11 +476,10 @@ bool config_open_default()
 	config_get_default_path(path);
 	if (config_open(path)) {
 		config_apply_to_old_addresses();
+		currency_load_custom_currency_config();
 		return true;
 	}
 
-	currency_load_custom_currency_config();
-
 	return false;
 }