Fixes: 619/clusterfuzz-testcase-5803914534322176
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 61ee2ca775)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>