Fixes: Timeout
Fixes: 6276/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMV1_fuzzer-5881196690014208

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>