* Enable the proxy to keep connections persistent in the HTTPS case.

  Basicly the persistence is created by keeping the conn_rec structure
  created for our backend connection (whether http or https) in the connection
  pool. This required to adjust scoreboard.c in a way that its functions can
  properly deal with a NULL scoreboard handle by ignoring the call or returning
  an error code.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@602542 13f79535-47bb-0310-9956-ffa450edef68