avformat/matroskadec: Fix infinite loop with bz decompression

The same check is added to zlib too, it seems not needed there though

Fixes: Infinite loop
Fixes: 43932/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-6175167573786624

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg


Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 9c3d2cbb)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>