Unimplement Send/Sync for ::env::{Args,ArgsOs,Vars,VarsOs}

Fixes #48004

…excrichton

Unimplement Send/Sync for ::env::{Args,ArgsOs,Vars,VarsOs}

Fixes rust-lang#48004

Rollup of 22 pull requests

- Successful merges: #47784, #47806, #47846, #48005, #48033, #48065, #48087, #48114, #48126, #48130, #48133, #48151, #48154, #48156, #48162, #48163, #48165, #48167, #48181, #48186, #48195, #48035
- Failed merges:

Rollup of 22 pull requests

- Successful merges: #47784, #47806, #47846, #48005, #48033, #48065, #48087, #48114, #48126, #48130, #48133, #48151, #48154, #48156, #48162, #48163, #48165, #48167, #48181, #48186, #48195, #48035
- Failed merges:

Rollup of 23 pull requests

- Successful merges: #47784, #47806, #47846, #48005, #48033, #48065, #48087, #48114, #48126, #48130, #48133, #48151, #48154, #48156, #48162, #48163, #48165, #48167, #48181, #48186, #48195, #48035, #48210
- Failed merges:

Correct a few stability attributes

* `const_indexing` language feature was stabilized in 1.26.0 by #46882
* `Display` impls for `PanicInfo` and `Location` were stabilized in 1.26.0 by #47687
* `TrustedLen` is still unstable so its impls should be as well even though `RangeInclusive` was stabilized by #47813
* `!Send` and `!Sync` for `Args` and `ArgsOs` were stabilized in 1.26.0 by #48005
* `EscapeDefault` has been stable since 1.0.0 so should continue to show that even though it was moved to core in #48735

This could be backported to beta like #49612

Move `sys::pal::os::Env` into `sys::env`

Although `Env` (as `Vars`), `Args`, path functions, and OS constants are publicly exposed via `std::env`, their implementations are each self-contained. Keep them separate in `std::sys` and make a new module, `sys::env`, for `Env`.

Also fix `unsafe_op_in_unsafe_fn` for Unix and update the `!DynSend` and `!DynSync` impls which had grown out of sync with the platforms (see rust-lang#48005 for discussion on that).

r? joboet

Tracked in rust-lang#117276.

Move `sys::pal::os::Env` into `sys::env`

Although `Env` (as `Vars`), `Args`, path functions, and OS constants are publicly exposed via `std::env`, their implementations are each self-contained. Keep them separate in `std::sys` and make a new module, `sys::env`, for `Env`.

Also fix `unsafe_op_in_unsafe_fn` for Unix and update the `!DynSend` and `!DynSync` impls which had grown out of sync with the platforms (see rust-lang#48005 for discussion on that).

r? joboet

Tracked in rust-lang#117276.

Rollup merge of rust-lang#140143 - thaliaarchi:move-env-pal, r=joboet

Move `sys::pal::os::Env` into `sys::env`

Although `Env` (as `Vars`), `Args`, path functions, and OS constants are publicly exposed via `std::env`, their implementations are each self-contained. Keep them separate in `std::sys` and make a new module, `sys::env`, for `Env`.

Also fix `unsafe_op_in_unsafe_fn` for Unix and update the `!DynSend` and `!DynSync` impls which had grown out of sync with the platforms (see rust-lang#48005 for discussion on that).

r? joboet

Tracked in rust-lang#117276.

Move `sys::pal::os::Env` into `sys::env`

Although `Env` (as `Vars`), `Args`, path functions, and OS constants are publicly exposed via `std::env`, their implementations are each self-contained. Keep them separate in `std::sys` and make a new module, `sys::env`, for `Env`.

Also fix `unsafe_op_in_unsafe_fn` for Unix and update the `!DynSend` and `!DynSync` impls which had grown out of sync with the platforms (see rust-lang#48005 for discussion on that).

r? joboet

Tracked in rust-lang#117276.