Fixes: signed integer overflow: 9223372036848019263 + 134232320 cannot be represented in type 'long'
Fixes: 48155/clusterfuzz-testcase-minimized-ffmpeg_dem_CINE_fuzzer-5751429207293952

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