After some productive feedback and no negative feedback, introduce
  SSLEngine upgrade so that we can begin and continue to support these
  facilities.  This makes it simpler to keep this effort (while we have
  no known clients that support Connection: upgrade at this time), and
  begin refactoring more of SSL into smaller and tighter (and then optional)
  components.

  Submitted by: Ryan Bloom
  Reviewed by: William Rowe, Joe Orton


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97912 13f79535-47bb-0310-9956-ffa450edef68