389-ds-base: 389-ds: anonymous ldap client can defeat selfdn aci bind-rule checks via empty bind dn

A flaw was found in 389 Directory Server. The SELFDN ACI bind-rule evaluator incorrectly matches an anonymous LDAP client's empty bind DN against an empty stored attribute value, allowing an unauthenticated client to satisfy access control checks intended to require a matching authenticated identity. This can allow an anonymous LDAP client to perform an operation, such as adding or modifying a directory entry, that a SELFDN-based ACI intended to restrict to a specific authenticated user.