PP/17 OpenSSL: new expansion var $tls_sni, which if used in tls_certificate
lets Exim select keys and certificates based upon TLS SNI from client.
+ Also option tls_sni on SMTP Transports. Also clear $tls_bits correctly
+ before an outbound SMTP session. New log_selector, +tls_sni.
+
+PP/18 Bugzilla 1122 - check localhost_number expansion for failure, avoid
+ NULL dereference. Report and patch from Alun Jones.
Exim version 4.77