xdg-output: schedule a wl_output.done event on update

Xwayland expects an xdg_output.done event to always be sent with a
wl_output.done event.

types/wlr_xdg_output_v1.c

@@ -55,6 +55,8 @@ static void output_update(struct wlr_xdg_output_v1 *xdg_output) {
 		wl_resource_for_each(resource, &xdg_output->resources) {
 			output_send_details(xdg_output, resource);
 		}
+
+		wlr_output_schedule_done(xdg_output->layout_output->output);
 	}
 }