client confirm server hostname in cert

client confirm server hostname in cert

Openssl v1.0.2 and above have support for checking the hostname
the client side connected to against the hostname on the cert the
server presented.

This enables that feature if the necessary API is available in the
openssl version, meaning the connection will fail at ssl negotiation if the
cert isn't for the requested server

It's very easy to test, add a fake entry to /etc/hosts for the server IP with
a different name, using that will fail at ssl but using the correct dns name
matching the certificate will work.