These limits are based on limiting done in WebRtcIlbcfix_CreateAugmentedVec()
Fixes: out of array accesses
Fixes: 10652/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ILBC_fuzzer-5638941487661056
Fixes: 10655/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ILBC_fuzzer-5699970020147200

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