[linux-cifs-client] cifs authentication change from 2.6.17 to 2.6.18 - default domain no longer null

[Steve French]

When I fixed the session structure to no longer include a fixed size 
domain name field (and instead allow it to be allocated on the fly) - 
this caused the default domain (when not specified on mount) to no 
longer be the empty string ("\0") and instead it was CIFS_LINUX_DOM with 
the result that servers which are not domain controllers or standalone 
servers or clients are confused by the non-existent domain.   The 
solution is easy, specify the domain name of the target server on the 
mount (e.g."domain=myserversdomame") but I do plan to change the 
behavior back to 2.6.17 behavior so it is less confusing