* add cputimer frame

* add cputime sleep

* ctime use cputime

* Processing cputime has no timeout function

* Migration cputime Code

* formatting file

* 整理代码

* add document copyright information

* 改 cputime_timer 为 cputimer

* 简化 _cputimer_list 初始化

* rt_cputimer_create -> rt_cputimer_init

* Remove RT_USING_CPUTIME and code cleanup.

* Remove RT_USING_CPUTIME in cputimer.c
* Set set_next_timeout as static function.

---------
Co-authored-by: NBernard Xiong <bernard.xiong@gmail.com>