RFC: patch to advapi32's cred tests

[Juan Lang]

> No, CRED_PERSIST_LOCAL_MACHINE should be fine but does this change
> make any difference? I believe the ERROR_NO_SUCH_LOGON_SESSION is
> returned when the tests are being run as a user that doesn't have a
> profile, and therefore the credentials manager doesn't have anywhere
> to store the credentials. Changing the persist type shouldn't affect
> this, so I don't see why it would make these calls start working.

I don't know whether it would make a difference, I don't see the
failures myself.  I just see a fairly consistent pattern of failure,
and reading MSDN made me suppose that a different persist type might
make a difference.

Never mind, I'll send the patch as-is then.  Thanks for the feedback.
--Juan