sh/rc-cgroup.sh: add openrc. prefix the cgroupv2 path

[ncopa]

Some services, like docker, creates and manages /sys/fs/cgroup/ themselves. Avoid conflict with the openrc created cgroup path by adding a openrc. prefix.

Fixes: #680

[donob4n]

It seems that it needs more changes for be fully coherent.

[Forza-tng]

Perhaps add a rc.conf variable for the openrc. prefix?

Would it make sense to create an opemrc group and nest all services below?

[williamh]

Hi,

I just applied this patch locally to test it and restarted a service.
I found that the old group for the service existed along side the new group after the restart.
e.g. /sys/fs/cgroup/ and /sys/fs/cgroup/openrc. both existed.
I was able to remove the old cgroup successfully.
Should we add something to this pr to removeit?

[ncopa]

Hi,

I just applied this patch locally to test it and restarted a service. I found that the old group for the service existed along side the new group after the restart. e.g. /sys/fs/cgroup/ and /sys/fs/cgroup/openrc. both existed. I was able to remove the old cgroup successfully. Should we add something to this pr to removeit?

Not sure its worth it. Its only a one time problem during upgrade that a reboot will "fix".