Listen: simplify code flow in listen_global_init()

src/Listen.cxx

@@ -82,18 +82,14 @@ void
 listen_global_init(ClientListener &listener)
 {
 	int port = config_get_positive(ConfigOption::PORT, DEFAULT_PORT);
-	const auto *param = config_get_param(ConfigOption::BIND_TO_ADDRESS);
 
 #ifdef ENABLE_SYSTEMD_DAEMON
 	if (listen_systemd_activation(listener))
 		return;
 #endif
 
-	if (param != nullptr) {
-		/* "bind_to_address" is configured, create listeners
-		   for all values */
-
-		do {
+	for (const auto *param = config_get_param(ConfigOption::BIND_TO_ADDRESS);
+	     param != nullptr; param = param->next) {
 		try {
 			listen_add_config_param(listener, port, param);
 		} catch (...) {
@@ -101,8 +97,9 @@ listen_global_init(ClientListener &listener)
 								  param->value.c_str(),
 								  param->line));
 		}
-		} while ((param = param->next) != nullptr);
-	} else {
+	}
+
+	if (listener.IsEmpty()) {
 		/* no "bind_to_address" configured, bind the
 		   configured port on all interfaces */