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.

av_free and friends are used in the ffmpeg plugin, and after r13528
ffmpeg's .pc files do not tell anymore to link needlessly to its
private library requirements.
Signed-off-by: Rémi Denis-Courmont <rem@videolan.org>

Including it after stdbool will cause compile failures as pointed by
Mike Frysinger in https://bugs.gentoo.org/show_bug.cgi?id=224289Signed-off-by: Rémi Denis-Courmont <rem@videolan.org>

Note: We may want to check that at configure time.

 in msg_Dbg.

This reverts commit 9ca4d542 which
introduces a segfault.