Merge r1419796 from trunk:

mod_proxy_balancer: It's totally unclear what Drn, Dis, Ign, Stby means. 
PR 52478
Submitted by: jailletc36
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1431329 13f79535-47bb-0310-9956-ffa450edef68