Fixes: Timeout (15sec -> 72ms)
Fixes: 17774/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALIAS_PIX_fuzzer-5193929107963904

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