compositor-rdp: Properly destroy the renderer and pixman image

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Armin Krezović <krezovic.armin@gmail.com>

libweston/compositor-rdp.c

@@ -542,6 +542,9 @@ rdp_output_disable(struct weston_output *base)
 	if (!output->base.enabled)
 		return 0;
 
+	pixman_image_unref(output->shadow_surface);
+	pixman_renderer_output_destroy(&output->base);
+
 	wl_event_source_remove(output->finish_frame_timer);
 	b->output = NULL;