lavc: remove disabled avcodec_decode_video() code

Fix warning:
libavcodec/utils.c: At top level:
libavcodec/utils.c:714:5: warning: "FF_API_VIDEO_OLD" is not defined

Also fix trac issue #139.

libavcodec/utils.c

@@ -710,23 +710,6 @@ static int64_t guess_correct_pts(AVCodecContext *ctx,
     return pts;
 }
 
-
-#if FF_API_VIDEO_OLD
-int attribute_align_arg avcodec_decode_video(AVCodecContext *avctx, AVFrame *picture,
-                         int *got_picture_ptr,
-                         const uint8_t *buf, int buf_size)
-{
-    AVPacket avpkt;
-    av_init_packet(&avpkt);
-    avpkt.data = buf;
-    avpkt.size = buf_size;
-    // HACK for CorePNG to decode as normal PNG by default
-    avpkt.flags = AV_PKT_FLAG_KEY;
-
-    return avcodec_decode_video2(avctx, picture, got_picture_ptr, &avpkt);
-}
-#endif
-
 int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
                          int *got_picture_ptr,
                          AVPacket *avpkt)