Final stage in this ldap commitathon. This fixes some problems

associated with processing of subgroup lists. There were some
problems that arose when the cache was referenced across possible
expirations. As of this fix the nested group code (and the caching
of queries related to nested groups) should be working correctly.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@600013 13f79535-47bb-0310-9956-ffa450edef68