avcodec/ffv1dec: consider run increase in minimal golomb frame size

Fixes: Timeout
Fixes: 49160/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-5672826144686080

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/ffv1dec.c

@@ -883,7 +883,10 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
         if (buf_size < avctx->width * avctx->height / (128*8))
             return AVERROR_INVALIDDATA;
     } else {
-        if (buf_size < avctx->height / 8)
+        int w = avctx->width;
+        for (int i = 0; w > (1<<ff_log2_run[i]); i++)
+            w -= ff_log2_run[i];
+        if (buf_size < (avctx->height + i + 6)/ 8)
             return AVERROR_INVALIDDATA;
     }