h264: return the consumed amountg in case of Q264

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/h264.c

@@ -4113,7 +4113,7 @@ not_extra:
     if(!(s->flags2 & CODEC_FLAG2_CHUNKS) && !s->current_picture_ptr){
         if (avctx->skip_frame >= AVDISCARD_NONREF ||
             buf_size >= 4 && !memcmp("Q264", buf, 4))
-            return 0;
+            return buf_size;
         av_log(avctx, AV_LOG_ERROR, "no frame!\n");
         return -1;
     }