Fix a reference to an uninitialized pointer in util_ldap_cache_init().

PR:                12091
Submitted by:      Jess Holle <jessh@ptc.com>
Reviewed by:	   Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96559 13f79535-47bb-0310-9956-ffa450edef68