to #26424323

Since we concern idle, let's take idle as the center state. And omit
transition between other stats. Below is the state transition graph:

                                sleep->deque
+-----------+ cpumask +-------+ exit->deque +-------+
|ineffective|-------- | idle  | <-----------|running|
+-----------+         +-------+             +-------+
                        ^ |
 unthrtl child -> deque | |
          wake -> deque | |thrtl chlid -> enque
       migrate -> deque | |migrate -> enque
                        | v
                      +-------+
                      | steal |
                      +-------+

We conclude idle state condition as:

!se->on_rq && !my_q->throttled && cpu allowed.

From this graph and condition, we can hook (de|en)queue_task_fair
update_cpumasks_hier, (un|)throttle_cfs_rq to account idle state.

In the hooked functions, we also check the conditions, to avoid
accounting unwanted cpu clocks.
Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>
Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Acked-by: NMichael Wang <yun.wang@linux.alibaba.com>