Merge r1826995, r1827001 from trunk:

Extend SSLOCSPEnable with mode 'leaf' that only checks the leaf of a
certificate chain. PR62112 [Ricardo Martin Camarero <rickyepoderi yahoo.es>] 

Fixed OCSPEnable to keep accepting "off", not "none".

Submitted by: icing
Reviewedby: icing, ylavic, rpluem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1834089 13f79535-47bb-0310-9956-ffa450edef68