Retrieve client connection information for ACL checks from the related HttpRequest...

Retrieve client connection information for ACL checks from the related HttpRequest object

This patch enable SSL client certificate ACL checks (user_cert and ca_cert)
in all cases the client connection information can retrieved from the related
HttpRequest object, eg when making peering decisions (peer_cache_access ACL).

Discussed under the "Supply client connection and IDENT information to
peer_cache_access ACL check" thread on squid-dev.

This is a Measurement Factory project