vcpu threads pin are implemented using sched_setaffinity(), but
not controlled by cgroup. This patch does the following things:

    1) enable cpuset cgroup
    2) reflect all the vcpu threads pin info to cgroup
Signed-off-by: NTang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: NHu Tao <hutao@cn.fujitsu.com>