avformat/utils: Avoid overflow in codec_info_duration computation for subtitles
Fixes: signed integer overflow:
9223126845747118112 - -
2594073385365397472 cannot be represented in type 'long'
Fixes: 34936/clusterfuzz-testcase-minimized-ffmpeg_dem_MATROSKA_fuzzer-
6739888002170880
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit
ffe4851e2359e17c4406ab05e2e31fc7ef68de95)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>