Merge the following revisions from trunk:

     trunk patch: http://svn.apache.org/r1588544 (rewrite+UDS)
                  http://svn.apache.org/r1641636 ('using default worker' msg tweak)
                  http://svn.apache.org/r1647005 (tcp reuse)
                  http://svn.apache.org/r1647009 (uds reuse)
                  http://svn.apache.org/r1647334 (uds reuse fix)


    + 1 additional de_socketfy call in mod_proxy





git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1651662 13f79535-47bb-0310-9956-ffa450edef68