Merge r379237 from trunk:

* Disable persistent connections for SSL backends again as we do not
  handle them correctly, because we recreate backend->connection for each
  request and thus try to initialize an already existing SSL connection.

Noticed by: jorton
Submitted by: rpluem
Reviewed by: rpluem, trawick, jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@390885 13f79535-47bb-0310-9956-ffa450edef68