Get mod_auth_ldap to retry connections on LDAP_SERVER_DOWN

PR:
Obtained from:
Submitted by:	Thomas Bennett <thomas.bennett@eds.com>
Reviewed by:	Graham Leggett


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96988 13f79535-47bb-0310-9956-ffa450edef68