Fixes: signed integer overflow: 155 + 2147483647 cannot be represented in type 'int'
Fixes: 23421/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LOCO_fuzzer-5652849097965568

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 3ddc5e1f3cebca25ade54ee68159d305f210bf5f)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>