Add many of the missing structs needed for using {get,set}_thread_status

[CraftSpider]

• I can revert the removal of the __ on x86_thread_state64_t, I went off of the fact that the structs are defined both with and without in the header, and that it adds a lot of unnecessary noise.
• The bitflag types API may not be perfect, I just went with something that worked
• This is still missing arm definitions, they can be added as another PR if desired

[JohnTitor]

Could you resolve merge conflicts? And it seems some structs' fields aren't marked as pub, is it intentional?

[CraftSpider]

Given the new arm code also uses the underscores, I'm leaning towards reverting that change. I'll spend some time writing up the manual implementations for the long arrays also, to fix the 1.33 build.

[CraftSpider]

Any other review requests for this? I'm not sure why the test failed, but it doesn't look immediately related. If it is, can I get a pointer in the right direction?

[JohnTitor]

Sorry for the delay!
The problem is that ctest2 uses old rustc's crates to parse and generate code.
Maybe there is an unsupported syntax (on older rustc) on the changes but I cannot find what it is 🤔