core: nm_singleton_instance_register() of NMManager instance

Register the singleton instance of NMManager as we do for other
singletons. That way, we get automatic destruction and the singleton
instance get's properly cleared (when the instance gets destroyed).

src/main.c

@@ -249,7 +249,6 @@ main (int argc, char *argv[])
 {
 	gboolean wifi_enabled = TRUE, net_enabled = TRUE, wwan_enabled = TRUE;
 	gboolean success = FALSE;
-	NMManager *manager = NULL;
 	NMConfig *config;
 	GError *error = NULL;
 	gboolean wrote_pidfile = FALSE;
@@ -402,10 +401,10 @@ main (int argc, char *argv[])
 
 	nm_auth_manager_setup (nm_config_get_auth_polkit (config));
 
-	manager = nm_manager_setup (global_opt.state_file,
-	                            net_enabled,
-	                            wifi_enabled,
-	                            wwan_enabled);
+	nm_manager_setup (global_opt.state_file,
+	                  net_enabled,
+	                  wifi_enabled,
+	                  wwan_enabled);
 
 	if (!nm_bus_manager_get_connection (nm_bus_manager_get ())) {
 		nm_log_warn (LOGD_CORE, "Failed to connect to D-Bus; only private bus is available");
@@ -424,9 +423,9 @@ main (int argc, char *argv[])
 
 	nm_dispatcher_init ();
 
-	g_signal_connect (manager, NM_MANAGER_CONFIGURE_QUIT, G_CALLBACK (manager_configure_quit), config);
+	g_signal_connect (nm_manager_get (), NM_MANAGER_CONFIGURE_QUIT, G_CALLBACK (manager_configure_quit), config);
 
-	if (!nm_manager_start (manager, &error)) {
+	if (!nm_manager_start (nm_manager_get (), &error)) {
 		nm_log_err (LOGD_CORE, "failed to initialize: %s", error->message);
 		goto done;
 	}
@@ -449,11 +448,9 @@ main (int argc, char *argv[])
 	if (configure_and_quit == FALSE)
 		g_main_loop_run (main_loop);
 
-	nm_manager_stop (manager);
+	nm_manager_stop (nm_manager_get ());
 
 done:
-	g_clear_object (&manager);
-
 	if (global_opt.pidfile && wrote_pidfile)
 		unlink (global_opt.pidfile);