Merge pull request #332 from emersion/gamma-control-fix-destroy

Remove gamma_control->link from list in destroy

types/wlr_gamma_control.c

@@ -15,6 +15,7 @@ static void gamma_control_destroy(struct wlr_gamma_control *gamma_control) {
 	wl_signal_emit(&gamma_control->events.destroy, gamma_control);
 	wl_list_remove(&gamma_control->output_destroy_listener.link);
 	wl_resource_set_user_data(gamma_control->resource, NULL);
+	wl_list_remove(&gamma_control->link);
 	free(gamma_control);
 }