Merge r1207467 from trunk:

"Final" (I hope) proxy struct/API changes in order to support
dynamic balancer allocation AND dynamic vhost-balancers
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1207468 13f79535-47bb-0310-9956-ffa450edef68