OSV-2021-821 Stack-buffer-overflow in jsoncons::bson::decimal128_to_chars

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=34816 Crash type: Stack-buffer-overflow WRITE 6 Crash state: jsoncons::bson::decimal128tochars jsoncons::bson::basicbsonparserjsoncons::binarystreamsource, std::1::allo...