macosx: playlist menu: use modern way to load xib

modules/gui/macosx/VLCPlaylist.h

@@ -29,7 +29,7 @@
 
 @interface VLCPlaylist : NSResponder<NSOutlineViewDelegate>
 
-@property (readwrite, weak) IBOutlet NSMenu *playlistMenu;
+@property (readwrite, strong) IBOutlet NSMenu *playlistMenu;
 @property (readwrite, weak) IBOutlet NSMenuItem *playPlaylistMenuItem;
 @property (readwrite, weak) IBOutlet NSMenuItem *deletePlaylistMenuItem;
 @property (readwrite, weak) IBOutlet NSMenuItem *infoPlaylistMenuItem;

modules/gui/macosx/VLCPlaylist.m

@@ -686,7 +686,7 @@
 - (NSMenu *)menuForEvent:(NSEvent *)o_event
 {
     if (!b_playlistmenu_nib_loaded)
-        b_playlistmenu_nib_loaded = [NSBundle loadNibNamed:@"PlaylistMenu" owner:self];
+        b_playlistmenu_nib_loaded = [[NSBundle mainBundle] loadNibNamed:@"PlaylistMenu" owner:self topLevelObjects:nil];
 
     NSPoint pt = [_outlineView convertPoint: [o_event locationInWindow] fromView: nil];
     NSInteger row = [_outlineView rowAtPoint:pt];