Our sysctl script has read from /etc/sysctl.d/ but the directory was not
created by default, and we didn't document it.
X-Gentoo-Bug: 398189
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=398189
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
