Add building support for Artix Linux (#16265)

Artix Linux is systemd free distribution based on Arch Linux, with
openrc dinit runit s6 as init alternatives. This patch will make
init scripts installation work the way Gentoo Linux with openrc.

The scripts tweaking for other init will be left to packager.

Signed-off-by: Yongming Zhao <ming.zym@gmail.com>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>