Merge r1633730 from trunk:

add OCSP Stapling configuration, disabled by default
Submitted by: trawick
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1634521 13f79535-47bb-0310-9956-ffa450edef68