Fixes: signed integer overflow: -2147483648 - 13 cannot be represented in type 'int'
Fixes: 18893/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ADPCM_IMA_APC_fuzzer-5630760442920960

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