Merge r1634120 from trunk:

* Use the correct server name for SNI in case the backend SSL connection itself
  is established via a proxy server.

PR: 57139
Submitted by: Szabolcs Gyurko <szabolcs gyurko.org>

Committed by: rpluem
Backported by: ylavic
Reviewed by: ylavic, wrowe, covener, orlikowski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1777779 13f79535-47bb-0310-9956-ffa450edef68