libcontainer: fix Checkpoint wrt cgroupv2
libcontainer: fix Checkpoint wrt cgroupv2

Commit 9a0184b10f474b meant to enable using cgroup v2 freezer
for criu >= 3.14, but it looks like it is doing something else
instead.

The logic here is:

 - for cgroup v1, set FreezeCgroup, if available
 - for cgroup v2, only set it for criu >= 3.14
 - do not use GetPaths() in case v2 is used
   (this method is obsoleted for v2 and will be removed)

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

mikebrow/runc,mikebrow/runc,opencontainers/runc,xiaochenshen/runc,estesp/runc,estesp/runc,dqminh/runc,rhatdan/runc,kolyshkin/runc,kolyshkin/runc,mikebrow/runc,opencontainers/runc,dqminh/runc,opencontainers/runc,kolyshkin/runc,dqminh/runc,rhatdan/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc,xiaochenshen/runc,estesp/runc,rhatdan/runc,xiaochenshen/runc,opencontainers/runc