cocoa: don't async redraw when waiting for VO redraw

This fixes the very annoying glitch where the black bars disappear for
a single frame when going fullscreen.

video/out/cocoa_common.m

@@ -720,6 +720,8 @@ int vo_cocoa_control(struct vo *vo, int *events, int request, void *arg)
 @synthesize vout = _video_output;
 
 - (void)performAsyncResize:(NSSize)size {
+    struct vo_cocoa_state *s = self.vout->cocoa;
+    if (!s->waiting_frame)
         vo_cocoa_resize_redraw(self.vout, size.width, size.height);
 }