librc: filter out container processes on OpenVZ host

Thanks to info and testing done by Daniel Robbins <drobbins@funtoo.org>,
there is now a fix for this. Below is his description of the steps
OpenRC needed to use.

1) See if /proc/<pid>/status exists
2) If it does, see if it has a "envID:" field
3) If it does, see if "envID:" is set to "0"
4) If so, then it's one of the host's processes and should be a
candidate for the list. Otherwise, it is one of the container's
processes and should be ignored.

This should fix the bug and allow start-stop-daemon to work properly on
OpenVZ hosts.

X-Gentoo-Bug: 376817
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=376817