macosx: fix main window appearing with a delay of some seconds

close #14361

(cherry picked from commit 8de7ac281107b742b40867b0694482bf9861effb)
Signed-off-by: David Fuhrmann <dfuhrmann@videolan.org>

modules/gui/macosx/intf.m

@@ -783,7 +783,10 @@ static VLCMain *_o_sharedMainInstance = nil;
     PL_UNLOCK;
 
     [NSBundle loadNibNamed:@"MainWindow" owner: self];
-    [o_mainwindow makeKeyAndOrderFront:nil];
+
+    // This cannot be called directly here, as the main loop is not running yet so it would have no effect.
+    // So lets enqueue it into the loop for later execution.
+    [o_mainwindow performSelector:@selector(makeKeyAndOrderFront:) withObject:nil afterDelay:0];
 
     [[SUUpdater sharedUpdater] setDelegate:self];
 }