Backport:

Bring the LDAPCacheEntries and LDAPOpCacheEntries usage() in synch with
the manual and the implementation (0 and -1 both disable the cache).
Submitted by: Eric Covener


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@815948 13f79535-47bb-0310-9956-ffa450edef68