Merge r1719257 from trunk:

Do not use the magic string "directory". Use the corresponding global variable as in all other places of the module.
Submitted by: jailletc36
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1725508 13f79535-47bb-0310-9956-ffa450edef68