res_stasis: Fix dial bridge unload.

If the dial bridge has been created it must be released by calling
ast_bridge_destroy, simply releasing the ao2 reference is not enough.

Also move stasis_app_control_shutdown earlier in unload to ensure the
bridge cannot be created or grabbed after the app_bridges container is
released.

Change-Id: I372302de94ca63876069e2585a049c5060e5e767

res/res_stasis.c

@@ -1992,6 +1992,9 @@ static int unload_module(void)
 	messaging_cleanup();
 
 	cleanup();
+
+	stasis_app_control_shutdown();
+
 	ao2_cleanup(apps_registry);
 	apps_registry = NULL;
 
@@ -2007,8 +2010,6 @@ static int unload_module(void)
 	ao2_cleanup(app_bridges_playback);
 	app_bridges_playback = NULL;
 
-	stasis_app_control_shutdown();
-
 	STASIS_MESSAGE_TYPE_CLEANUP(end_message_type);
 	STASIS_MESSAGE_TYPE_CLEANUP(start_message_type);
 

res/stasis/control.c

@@ -1507,7 +1507,9 @@ void stasis_app_control_shutdown(void)
 {
 	ast_mutex_lock(&dial_bridge_lock);
 	shutting_down = 1;
-	ao2_cleanup(dial_bridge);
-	dial_bridge = NULL;
+	if (dial_bridge) {
+		ast_bridge_destroy(dial_bridge, 0);
+		dial_bridge = NULL;
+	}
 	ast_mutex_unlock(&dial_bridge_lock);
 }