MSFT NFSv3 fakes DOS attributes based on file type and permissions.
Rather than just faking FILE_ATTRIBUTE_DIRECTORY for dirs, fetch the
"real" DOS attributes returned by NFS.
This allows to handle the "R/O" attribute on shortcut files and thus
reading and creating device shortcut files on NFS.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>