[patch] Option to supress auto guest login in libsmbclient

[Nielsen]

I'm working on the gnome-vfs smb module. One thing that gets in the way 
is when that when a user types an invalid password, libsmbclient tries 
to login as Guest. It appears to gnome-vfs and the user that the login 
worked, when in fact it didn't, and more often than not the user has the 
wrong access privileges.

This behavior also prevents us from refactoring the gnome-vfs smb code 
in a more stable way.

Attached to this bug report is a patch which adds an option to suppress 
this behavior. It should be API/ABI compatible:

https://bugzilla.samba.org/show_bug.cgi?id=2092

It would be great to get this included in the next SAMBA_3_0 and 
SAMBA_3_1 release.

Cheers,
Nate