sys-process/rtirq: version bump to 20180209

sys-process/rtirq: version bump to 20180209

- Install systemd service file.
- Bump to EAPI 7.
- Drop explicit RDEPEND on sys-apps/util-linux.
- Group variables as in skel.ebuild.
- Update LICENSE to GPL-2+ in accordance with rtirq.sh.
- Do not use PN variable in src_install.
- Remove OpenRC specific code that was not very useful anyway.
- Use KV_LOCAL from linux-info to detect if the current kernel is
  realtime or not.
- Avoid using grep unnecessarily.

Closes: https://bugs.gentoo.org/653732
Signed-off-by: Karl Linden <karl.j.linden@gmail.com>
Package-Manager: Portage-2.3.51, Repoman-2.3.11
Closes: https://github.com/gentoo/gentoo/pull/10135
Signed-off-by: Michał Górny <mgorny@gentoo.org>