…ove-autosplats

…r=workingjubilee

Sync portable-simd for bitmasks &c.

In the ideal case, where everything works easily and nothing has to be rearranged, it is as simple as:
- `git subtree pull -P library/portable-simd https://github.com/rust-lang/portable-simd - ${branch}`
- write the commit message
- `python x.py test --stage 1` to make sure it runs
- `git push` to your PR-to-rustc branch

If anything borks up this flow, you can fix it with sufficient git wizardry but you are usually better off going back to the source, fixing it, and starting over, before you open the PR.

r? `@calebzulawski`

This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.

A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).

It looks like the last time had left some remaining cfg's -- which made me think
that the stage0 bump was actually successful. This brings us to a released 1.62
beta though.

This PR will fix some typos detected by [typos].

I only picked the ones I was sure were spelling errors to fix, mostly in
the comments.

[typos]: https://github.com/crate-ci/typos

These were likely from before the `PartialEq<str>` impl for `&String`.

Sync up to rust-lang/portable-simd@8527625

Co-authored-by: Jacob Lifshay <programmerjake@gmail.com>

…number casts to number traits.

…er]` to ones with runtime panics from user input

Add `#[inline]` to functions which were missing it, and `#[track_caller]` to ones with runtime panics from user input

rust-lang/cargo#10910 starts emitting warning if resolver is not set
for 2021 edition package. We want to surpress the warning for now.

Remove cast_ptr in favor of cast which acts like pointer::cast (and adjust integer casts)

Fix build error on big endian arm/aarch64

Add a prelude

Sync upstream

Sync up to rust-lang/portable-simd@7c7dbe0

Old fn were slightly divergent.