Fixes: 32121/clusterfuzz-testcase-minimized-ffmpeg_IO_DEMUXER_fuzzer-4512973109460992
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 6055b93379fd29477afa8f24881223a14e2f6b81)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>