do not umount /usr on linux systems
do not umount /usr on linux systems

We can't really umount /usr on linux systems because /usr is a special
case if it is a separate filesystem which is handled by an initramfs.

reported-by: f49674f8f94d7a5646e06b799adb47003ce626ae@kyomu.43-1.org
X-Gentoo-Bug: 415523
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=415523

dwfreed/openrc,williamh/openrc,dwfreed/openrc,williamh/openrc,OpenRC/openrc,dwfreed/openrc,OpenRC/openrc,OpenRC/openrc,williamh/openrc