sched/fair: introduce SCHED_STEAL

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8PIYZ


CVE: NA

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Introduce CONFIG_SCHED_STEAL to limit the impact of steal task.

1). If turn off CONFIG_SCHED_STEAL, then all the changes will not
exist, for we use some empty functions, so this depends on compiler
optimization.

2). enable CONFIG_SCHED_STEAL, but disable STEAL and schedstats, it
will introduce some impact whith schedstat check. but this has little
effect on performance. This will be our default choice.

Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Cheng Yu <serein.chengyu@huawei.com>