Previously, we drop connection if server certificate verification
fails after handshake.  With this commit, we fail handshake if that
happens.

This reverts commit b4337d1b.

nghttpx: Retry getaddrinfo without AI_ADDRCONFIG

Escape access log

src: BoringSSL supports SSL_CTX_set_{min,max}_proto_version.

The certain characters coming from client are now escaped with "\xNN"
where NN is the ascii code of the character in hex notation.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

asio: client: Send PING after 30 seconds idle

This reverts commit f69b52b1.