Stop registering a cleanup on each LDAP connection created, this cleanup was

never called because it's registered against pconf in the child. LDAP
connections are created in the child and not shared between children, so no
action should be required at child exit

Additionally, clarify comments around uldap_connection_cleanup()



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@592764 13f79535-47bb-0310-9956-ffa450edef68