Fixes: Memleaks
Fixes: 17219/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5720539124989952

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 9a0d36e5)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>