Perhaps we should turn it into ...New() and do more than just allocate
the object.

(You get to love va_list type-safety)

The rationale is the same as with vlc_object_find().

Remove a bunch of ( vlc_object_t * )vlc_object_find( p_intf, VLC_OBJECT_VOUT, FIND_ANYWHERE );
and FIND_CHILD there.