libinput: make setting the same output a no-op

In the future evdev_device_set_output() will start getting called more
often, redundantly. Short-circuit the setting if the chosen output is
already set for an input device. This reduces churn in the logs.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

libweston/libinput-device.c

@@ -549,6 +549,9 @@ void
 evdev_device_set_output(struct evdev_device *device,
 			struct weston_output *output)
 {
+	if (device->output == output)
+		return;
+
 	if (device->output_destroy_listener.notify) {
 		wl_list_remove(&device->output_destroy_listener.link);
 		device->output_destroy_listener.notify = NULL;