Fix 0448c670 as I forgot to use pl_Yield instead of vlc_object_find.
And fix some other use of vlc_object_find for the playlist.

We end up looking up from p_libvlc anyway, so we might as well as well
do it from the beginning

Pointed out by Hannes Domani

Actually, we just need to do like Direct3D: catch left-click.

lamers

Signed-off-by: Rafaël Carré <funman@videolan.org>

Speeds up vlc_list_find(), as we avoid looking up the 200+ plugins for
each vlc_list_find(). Also avoids accidentally stealing objects across
LibVLC instances. IMHO, the object tree should be per-instance, and the
root object should not exist, but that's too big a change yet.

(main remaining offenders: vlc_interface.h and vlc_network.h)