+JH/04 Fix TLS resumption for TLS-on-connect. This was broken by the advent
+ of loadbalancer-detection for resumption, in 4.96 - which tries to
+ use the EHLO response. SMTPS does not have one at the time it is starting
+ TLS. Change the default for the smtp transport host_name_extract option
+ to be a static string, for TLS-on-connect cases; meaning that resumption
+ will always be attempted (unless deliberately overriden).
+