macosx: fixed rare crash when reshaping the video view (fixes #5740)

(cherry picked from commit 52eae1b9)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/macosx/intf.m

@@ -1645,7 +1645,7 @@ unsigned int CocoaKeyToVLC( unichar i_key )
 {
     b_active_videoplayback = b_value;
     [o_mainwindow setVideoplayEnabled];
-    [o_mainwindow togglePlaylist:nil];
+    [o_mainwindow performSelectorOnMainThread:@selector(togglePlaylist:) withObject: nil waitUntilDone:NO];
 }
 
 - (BOOL)activeVideoPlayback