Use a separate interface for loggers.

The new interface does not allow loggers to unregister themselves from
the bus.  This allows us to use a rwlock_t for them.

The latter also means that loggers can now be called concurrently by
multiple threads.

src/libcharon/plugins/android/android_logger.c

@@ -41,7 +41,7 @@ struct private_android_logger_t {
 };
 
 
-METHOD(listener_t, log_, bool,
+METHOD(logger_t, log_, void,
 	   private_android_logger_t *this, debug_t group, level_t level,
 	   int thread, ike_sa_t* ike_sa, char *format, va_list args)
 {
@@ -64,8 +64,6 @@ METHOD(listener_t, log_, bool,
 			current = next;
 		}
 	}
-	/* always stay registered */
-	return TRUE;
 }
 
 METHOD(android_logger_t, destroy, void,
@@ -83,7 +81,7 @@ android_logger_t *android_logger_create()
 
 	INIT(this,
 		.public = {
-			.listener = {
+			.logger = {
 				.log = _log_,
 			},
 			.destroy = _destroy,

src/libcharon/plugins/android/android_logger.h

@@ -31,9 +31,9 @@ typedef struct android_logger_t android_logger_t;
 struct android_logger_t {
 
 	/**
-	 * Implements bus_listener_t interface
+	 * Implements logger_t interface
 	 */
-	listener_t listener;
+	logger_t logger;
 
 	/**
 	 * Destroy the logger.

src/libcharon/plugins/android/android_plugin.c

@@ -68,7 +68,7 @@ METHOD(plugin_t, destroy, void,
 	hydra->attributes->remove_handler(hydra->attributes,
 									  &this->handler->handler);
 	lib->credmgr->remove_set(lib->credmgr, &this->creds->set);
-	charon->bus->remove_listener(charon->bus, &this->logger->listener);
+	charon->bus->remove_logger(charon->bus, &this->logger->logger);
 	this->creds->destroy(this->creds);
 	this->handler->destroy(this->handler);
 	this->logger->destroy(this->logger);
@@ -98,7 +98,7 @@ plugin_t *android_plugin_create()
 	this->service = android_service_create(this->creds);
 	this->handler = android_handler_create(this->service != NULL);
 
-	charon->bus->add_listener(charon->bus, &this->logger->listener);
+	charon->bus->add_logger(charon->bus, &this->logger->logger);
 	lib->credmgr->add_set(lib->credmgr, &this->creds->set);
 	hydra->attributes->add_handler(hydra->attributes, &this->handler->handler);