macosx: close the right window when pressing Cmd+W

For nonembedded mode, this makes sure that:
- playlist window can be closed and video continues playing
- video will be stopped when closing video window with Cmd+W

Close #6239
Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>
(cherry picked from commit cf461cc0)

modules/gui/macosx/MainWindow.m

@@ -800,14 +800,21 @@ static VLCMainWindow *_o_sharedInstance = nil;
 
 - (void)performClose:(id)sender
 {
+    NSWindow *o_key_window = [NSApp keyWindow];
+
     if (b_dark_interface)
     {
-        [self orderOut: sender];
-        if ([[VLCMain sharedInstance] activeVideoPlayback] && !b_nonembedded)
+        [o_key_window orderOut: sender];
+        if ( [[VLCMain sharedInstance] activeVideoPlayback] && ( !b_nonembedded || o_key_window != self ))
             [[VLCCoreInteraction sharedInstance] stop];
     }
     else
-        [super performClose: sender];
+    {
+        if( b_nonembedded && o_key_window != self )
+            [o_nonembedded_window performClose: sender];
+        else
+            [super performClose: sender];
+    }
 }
 
 - (void)performMiniaturize:(id)sender