libct/cg/sd/v1: Set: don't overwrite r.Freezer
libct/cg/sd/v1: Set: don't overwrite r.Freezer

m.Freeze method changes m.cgroups.Resources.Freezer field, which should
not be done while we're temporarily freezing the cgroup in Set. If this
field is changed, and r == m.cgroups.Resources (as it often happens),
this results in inability to freeze the container using Set().

To fix, add and use a method which does not change r.Freezer field.

A test case for the bug will be added separately.

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

rhatdan/runc,opencontainers/runc,opencontainers/runc,dqminh/runc,rhatdan/runc,dqminh/runc,kolyshkin/runc,opencontainers/runc,rhatdan/runc,rhatdan/runc,kolyshkin/runc,opencontainers/runc,dqminh/runc,kolyshkin/runc,kolyshkin/runc,dqminh/runc