support for mknod to windows now in cifs vfs

[Steve French]

I added the code to cifs vfs to enable it do mknod of block and 
chardevice even if the server does not support the Unix extensions (such 
as Windows).  This requires the "sfu" mount option to be specified and 
these will be recognized in Windows in the services for unix shells.   
There is also code now in the cifs vfs that can retrieve the special 
mode bits (the three above 0777) but not set them yet.

This code is in the cifs-2.6.git tree on kernel.org.   I will make a 
tar.gz of current cifs code later in the week.