OSV-2019-1 ASSERT: bufferRemainingSize() >= length.

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18431 Crash type: ASSERT Crash state: bufferRemainingSize = length. Envoy::Http::Http1::ConnectionImpl::copyToBuffer Envoy::Http::Http1::RequestStreamEncoderImpl::encodeHeaders...