Automatically unload pre-defined empty zone if the real master zone is in LDAP.
BIND version 9.9 automatically loads all empty zones defined
in RFC 6303. This prevents bind-dyndb-ldap from loading real
master zone from LDAP.
https://fedorahosted.org/bind-dyndb-ldap/ticket/119
Signed-off-by: Petr Spacek <pspacek@redhat.com>