Allow decoders to set AVCodecContext.refs.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@16305 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/avcodec.h

@@ -2082,7 +2082,7 @@ typedef struct AVCodecContext {
     /**
      * number of reference frames
      * - encoding: Set by user.
-     * - decoding: unused
+     * - decoding: Set by lavc.
      */
     int refs;