Fixes: signed integer overflow: 2117181180 + 60483298 cannot be represented in type 'int'
Fixes: 18344/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5685327791915008

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>