Merge r1387088 from trunk:

Add in new type CLEARINUSE which allows the inuse table to
be cleared upon storage. This may be expected/wanted/required
by some applications

Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1394021 13f79535-47bb-0310-9956-ffa450edef68