cifs: use Minshall+French symlink functions

If configured, Minshall+French Symlinks are used against
all servers. If the server supports UNIX Extensions,
we still create Minshall+French Symlinks on write,
but on read we fallback to UNIX Extension symlinks.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>