text-backend: Don't restart client on exit

When we're shutting down, don't try to restart the IM client.

Signed-off-by: Daniel Stone <daniels@collabora.com>

compositor/text-backend.c

@@ -988,6 +988,8 @@ input_method_client_notifier(struct wl_listener *listener, void *data)
 				    client_listener);
 
 	text_backend->input_method.client = NULL;
+
+	if (!text_backend->compositor->shutting_down)
 		respawn_input_method_process(text_backend);
 }