Fixes: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int'
Fixes: 22975/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_LOCO_fuzzer-5658160970072064

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 aa88cdfd90f5da0683cd6556c75a5ba5740a1c27)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>