Fixes: signed integer overflow: -2147483360 - 631 cannot be represented in type 'int'
Fixes: 17701/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ADPCM_IMA_EA_EACS_fuzzer-5711517319692288

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