r6720: added support for the remaining 2 types of CLDAP netlogon

r6720: added support for the remaining 2 types of CLDAP netlogon
response.

To work around the fact that the type of the returned data is not
encoded in the packet, this required adding ndr_pull_union_blob()
which allows us to pull a blob into a union with a specified switch
value, in this case the switch value comes from the calling NtVer field.
(This used to be commit bd27e626c27be72913d1a1569ee6e2e2711df84e)