avcodec/h264: do proper cleanup in ff_h264_alloc_tables() in case DPB alloc fails

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

libavcodec/h264.c

@@ -473,7 +473,7 @@ int ff_h264_alloc_tables(H264Context *h)
     if (!h->DPB) {
         h->DPB = av_mallocz_array(H264_MAX_PICTURE_COUNT, sizeof(*h->DPB));
         if (!h->DPB)
-            return AVERROR(ENOMEM);
+            goto fail;
         for (i = 0; i < H264_MAX_PICTURE_COUNT; i++)
             av_frame_unref(&h->DPB[i].f);
         av_frame_unref(&h->cur_pic.f);