Revert "include/vlc_picture.h: Add pf_private_release() callback"

This reverts commit cede8daf.

include/vlc_picture.h

@@ -99,7 +99,6 @@ struct picture_t
     /** Private data - the video output plugin might want to put stuff here to
      * keep track of the picture */
     picture_sys_t * p_sys;
-    void (*pf_private_release)( picture_t * );
 
     /** This way the picture_Release can be overloaded */
     void (*pf_release)( picture_t * );
@@ -178,8 +177,6 @@ static inline picture_t *picture_Hold( picture_t *p_picture )
  */
 static inline void picture_Release( picture_t *p_picture )
 {
-    if( p_picture->pf_private_release )
-        p_picture->pf_private_release( p_picture );
     /* FIXME why do we let pf_release handle the i_refcount ? */
     if( p_picture->pf_release )
         p_picture->pf_release( p_picture );