Fixes: Timeout (28sec -> 3sec)
Fixes: 17559/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_H263_fuzzer-5681050776240128

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 7f0498ed)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>