Make ldap_parse_rrentry() idempotent.
    
    Now, a call to ldap_parse_rrentry() resets the internal entry
    interators in ldap_entry_t so the results are always correct.
    
    Without this patch, a second call returned empty ldapdb_rdatalist_t
    because all iterators were at the end of internal lists.
    
    Signed-off-by: Petr Spacek <pspacek@redhat.com>