Log Message:
Nghttp2 v1.21.0

libnghttp2
----------
The bug that nghttp2_session_want_write may return 0 if there is pending frames \ 
after GOAWAY frame is submitted has been fixed.

build
-----
_U_ macro has been eliminated in favor of old school (void)VAR for better \ 
compiler compatibility.

libnghttp2_asio
---------------
The asio client now sends PING frame when it gets idle for 30 seconds.

src
---
Mozilla’s “Modern compatibility” ciphers are used by default.

nghttpx
-------
The bug that -v option does not print out version number has been fixed.

The workaround of getaddrinfo failure with AI_ADDRCONFIG has been applied.

nghttpx now escapes certain characters in access log.

nghttpx now enables backend pattern matching with --http2-proxy option as well.