Revert "app: [macOS] pace display link"

This reverts commit 11f39582b8 that
introduced pacing of display link callbacks. Blocking the display link
callback introduced deadlocks with code that updates the display link
display.

Not pacing the display link may introduce extra view invalidations,
but invalidates are consolidated by the system and won't result in
extra redraws.

Fixes: https://todo.sr.ht/~eliasnaur/gio/370
Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/os_macos.go

@@ -794,14 +794,10 @@ func newOSWindow() (*window, error) {
 		view:  view,
 		scale: scale,
 	}
-	done := make(chan struct{})
-	setNeedsDisplay := func() {
-		C.setNeedsDisplay(w.view)
-		done <- struct{}{}
-	}
 	dl, err := NewDisplayLink(func() {
-		w.runOnMain(setNeedsDisplay)
-		<-done
+		w.runOnMain(func() {
+			C.setNeedsDisplay(w.view)
+		})
 	})
 	w.displayLink = dl
 	if err != nil {