macosx: Fix a typo that leads to a crash in _removeOldPreferences.

modules/gui/macosx/intf.m

@@ -2292,7 +2292,7 @@ end:
         return;
     }
 
-    NSArray * ourPreferences = [NSArray arrayWithObjects:@"org.videolan.vlc.plist", @"VLC"];
+    NSArray * ourPreferences = [NSArray arrayWithObjects:@"org.videolan.vlc.plist", @"VLC", nil];
 
     /* Move the file to trash so that user can find them later */
     [[NSWorkspace sharedWorkspace] performFileOperation:NSWorkspaceRecycleOperation source:preferences destination:nil files:ourPreferences tag:0];