Merge r1818040 from trunk:

PR61891: looping over mostly full LDAP cache

  *) mod_ldap: Fix a case where a full LDAP cache would continually fail to
     purge old entries and log AH01323. PR61891.


Submitted By: Hendrik Harms <hendrik.harms gmail.com>
Committed By: covener
Reviewed By: covener, jim, ylavic


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1820800 13f79535-47bb-0310-9956-ffa450edef68