macos 4.0: libvlc_media_player_set_nsobject doesn't work correctly anymore

Creating a libvlc media player and assigning an NSObject was resulting to the display failing to open correctly. As far as I see, it's a regression from ce06f6c4.

It was fixed with the merge of the window_macosx module which would Open as a separate window anyway, and result in an external black window controlling the embedded view, with the rendering happening in the embedded view instead, which is not correct either.