xinetd: Update to version 2.3.15.4

xinetd: Update to version 2.3.15.4

- This is v2 version of this patch with the locations for the sysconf and binaries
   corrected so that all files are in the same locations as they were with version 2.3.15
   Added sysconfdir and bindir to the configure options to achieve this.
- Update from version 2.3.15 (2012) to 2.3.15.4 (2018)
- Update of rootfile.
- The original site for xinetd is no longer accessible.
- Version 2.3.15 was the last version from  https://github.com/xinetd-org/xinetd
   OpenSUSE have forked the repo and have provided 2.3.15.3 and 2.3.15.4 to collect a range
    of patches together from openSUSE, Debian, Fedora, Gentoo etc.
   Last bug fix was done on this github repo in Sep 2022 and the last commit in Oct 2022.
- This is as up to date as there is currently available.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>