Add a check to ensure that the server returns the correct device type, not

Add a check to ensure that the server returns the correct device type, not
just the correct error.

This should help us avoid breaking NT4 IPC$ connections, for example.

This has required that we don't overwrite the device type for IPC$ in our
tcon&X code, but only smbwrapper even uses it, and a server that doesn't send
a correct dev type breaks other things pretty badly.

In any case, I'll 'fix' smbwrapper :-).

Andrew Bartlett