metal: emulate vblank events on the nvidia driver

src/tasks/connector.rs

@@ -32,6 +32,7 @@ pub fn handle(state: &Rc<State>, connector: &Rc<dyn Connector>) {
         drm_dev: drm_dev.clone(),
         async_event: Rc::new(AsyncEvent::default()),
         damaged: Cell::new(false),
+        needs_vblank_emulation: Cell::new(false),
     });
     if let Some(dev) = drm_dev {
         dev.connectors.set(id, data.clone());