The difference between them are former has const qualifier to the |in|
parameter, which is desirable since it is effectively read-only.

* don't use CRYPTO_LOCK stuff (they are sorted out by openssl, and no
  application intervention is required, just like boringSSL)
* don't use OPENSSL_config
* use provided API to access BIO member

We enabled libev kqueue backend in nghttpx by default.  Since it might
not work on some platforms, we also added --no-kqueue option to
disable it.

The --backend-tls-sni-field is deprecated in favor of sni keyword.
--backend-tls-sni-field still works, and it overrides all sni keyword
in --backend option.  But it will be removed in the future release.