Auto merge of #84115 - CDirkx:rt, r=m-ou-se

2021-04-25T04:45:39+00:00

Rework `init` and `cleanup` This PR reworks the code in `std` that runs before and after `main` and centralizes this code respectively in the functions `init` and `cleanup` in both `sys_common` and `sys`. This makes is easy to see what code is executed during initialization and cleanup on each platform just by looking at e.g. `sys::windows::init`. Full list of changes: - new module `rt` in `sys_common` to contain `init` and `cleanup` and the runtime macros. - `at_exit` and the mechanism to register exit handlers has been completely removed. In practice this was only used for closing sockets on windows and flushing stdout, which have been moved to `cleanup`. - ~~On windows `alloc` and `net` initialization is now done in `init`, this saves a runtime check in every allocation and network use.~~

Explicitly implement `!Send` and `!Sync` for `sys::{Args, Env}`

2021-04-22T22:15:35+00:00

Move most init to `sys::init`

2021-04-22T16:00:12+00:00

Remove `sys::args::Args::inner_debug` and use `Debug` instead

2021-04-22T09:04:29+00:00

Move all cleanup to `sys::cleanup`

2021-04-22T08:44:44+00:00

mv std libs to library/