samba-tool: Remove --use-xattrs support without --use-ntvfs

samba-tool: Remove --use-xattrs support without --use-ntvfs

The only reasonable use --use-xattrs=no should be used is in selftest,
and there is no need for that or --use-xattrs=auto without
--use-ntvfs, all systems we support in production for the AD DC have
xattrs, as using smbd needs posix ACLs.

This also removes the option entirely if NTVFS support is omitted from
the build.

I would prefer to get rid of the option, but currently selftest relies
on the default of --use-xattrs=auto, and we first should get rid of
that auto-detection, which will then mean we need --use-xattrs=no
specified wherever we specify --use-ntvfs.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Autobuild-User(master): Garming Sam <garming@samba.org>
Autobuild-Date(master): Tue Sep  6 04:21:42 CEST 2016 on sn-devel-144