macosx: Sanitization. Suppress non-sense yield(->p_input) release(->p_input), invalid...

macosx: Sanitization. Suppress non-sense yield(->p_input) release(->p_input), invalidate the manage thread, make sure we don't re-run a timer when the interface is dead. (Shoot 'em up!)

Remember, you can't assume that in your thread an object is alive if you don't delimit want-to-be safe place by a lock(p_obj)/unlock(p_obj).
Also, yield(p_playlist->p_input) is invalid if you don't lock the playlist before. The correct way here is to use vlc_object_find() as the locking policy of the playlist is not safe.