if 0 is encountered in the LUT then decompress() will continue to output 0 bytes but never read more data.
Without a specification it is impossible to say if this is invalid or a feature.
None of the valid prosumer files tested cause a 0 to be read, so it is likely
not a intended feature.

Fixes: Timeout
Fixes: 11266/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PROSUMER_fuzzer-5681827423977472

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