Ticket #48016 - search, matching rules and filter error "unsupported type 0xA9"
    
    Description: Since extensible filter (LDAP_FILTER_EXTENDED) was not
    implemented in slapi_filter_to_string_internal, it issued a bogus
    message "unsupported type 0xA9" which could be logged in the error
    log and confuse the troubleshooting.
    
    This patch adds the case LDAP_FILTER_EXTENDED to slapi_filter_to_
    string{_internal}.
    
    https://fedorahosted.org/389/ticket/48016
    
    Reviewed by rmeggins@redhat.com (Thank you, Rich!!)