WIP: online cpu can be bind by sched_getaffinity()

[lhanjian]

nginx's automatic core binding will only bind the cores sequentially from head to tail, and will not obtain the current online cpu.

https://forum.nginx.org/read.php?29,279564,279569#msg-279569

Similar needs and discussions in the nginx community

[chobits]

I convert this PR to draft. There are some compilation error found by test cases. If your pr is ready to review, click ready to review in this page.

[chobits]

TODO: also need to create documentation for this feature