xinetd: 2.3.15 -> 2.3.15.4

This is updating from an old version from abandoned upstream repo to
an actively maintained opensuse fork, hence all the changes and cleanups.

License-Update: added suse copyrights
Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>