s3-vfs-streams_xattr: add close call

s3-vfs-streams_xattr: add close call

https://bugzilla.samba.org/show_bug.cgi?id=13725

We cannot always rely on vfs_default to close the fake fds. This mostly is
relevant when used with another non-local VFS filesystem module such as
gluster.

Guenther

Signed-off-by: Günther Deschner <gd@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu Dec 20 07:18:20 CET 2018 on sn-devel-144

(cherry picked from commit 1b263ed631c86bf4117c9388fce3fa1f24cea4c9)