[Samba] Export Samba mount using nfs

[Adam Nielsen]

> Generally speaking, it is a fundamental security tenet of NFS that you
> cannot re-export a filesystem you have mounted from another system to
> still other systems.  I don't know if this applies to smb-mounted
> filesystems.

I've only seen this happen when the mountpoint was inside an exported
filesystem.  If you explicitly export the mountpoint it seems to work
(e.g. exporting /mnt will make a few empty folders available via NFS,
but exporting /mnt/blah explicitly will make the entire /mnt/blah
filesystem available over NFS.)

Cheers,
Adam.