avcodec/utils: correct align value for interplay

Fixes out of array access
Fixes: 452/fuzz-1-ffmpeg_VIDEO_AV_CODEC_ID_INTERPLAY_VIDEO_fuzzer

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
int ff_thread_ref_frame(ThreadFrame *dst, ThreadFrame *src)
{
    int ret;

    dst->owner = src->owner;

    ret = av_frame_ref(dst->f, src->f);
    if (ret < 0)
        return ret;

    av_assert0(!dst->progress);

    if (src->progress &&
        !(dst->progress = av_buffer_ref(src->progress))) {
        ff_thread_release_buffer(dst->owner, dst);
        return AVERROR(ENOMEM);
    }

    return 0;
}

int ff_thread_ref_frame(ThreadFrame *dst, ThreadFrame *src)
{
    int ret;

    dst->owner = src->owner;

    ret = av_frame_ref(dst->f, src->f);
    if (ret < 0)
        return ret;

    av_assert0(!dst->progress);

    if (src->progress &&
        !(dst->progress = av_buffer_ref(src->progress))) {
        ff_thread_release_buffer(dst->owner, dst);
        return AVERROR(ENOMEM);
    }

    return 0;
}
