Path of cgroup is wrong when running a container in a container. Use
the root path of mountinfo fetched from /proc/$(shim_pid)/mountinfo
to trim the path obtained from /proc/self/mountinfo.
Fixes: #131
Signed-off-by: 乔琛 10307740 <qiao.chen@zte.com.cn>
Delete check_support and stop detecting subsystems by finding in the
root folders because the detecting method is not accurate.
Signed-off-by: Tim Zhang <tim@hyper.sh>
