The merge request shown below prompted (thankfully) an
examination of our lxc containers logic in readproc.c.

As it turns out, the lxc folks changed that eyecatcher
used to identify containers within a task cgroup file.

So this patch, with little extra cost, will enable the
libprocps lxc_containers() guy to handle both strings.

[ additionally, I was shocked to find lxc allows the ]
[ eyecatcher to be changed at ./configure time. such ]
[ a provision has always existed. unfortunately, the ]
[ changed value was only available to root, assuming ]
[ one wished to tackle that undocumented liblxc api. ]

Reference(s):
. what prompted lxc support reevaluation
procps-ng/procps!82


. original lxc support introduced
commit 0557504f

Signed-off-by: Jim Warner <james.warner@comcast.net>