remove unnecessary relocation check in const_prop

Unnecessary as per https://github.com/rust-lang/rust/issues/70356#issuecomment-606615292

Fixes https://github.com/rust-lang/rust/issues/70356
r? @oli-obk Cc @wesleywiser

Clean up E0466 explanation

r? @Dylan-DPC

Ensure there are versions of test code for aarch64 windows

Remove the `cfg` flags that were preventing some tests from running on `aarch64-pc-windows-msvc`.

All the existing `target_os = windows` targets had the same `align()` and `size()` values, so this change just removes the `target_arch` flags.

r? @alexcrichton

Document ThreadSanitizer in unstable-book

improve folder name for persistent doc tests

This fixes #69411, by using the entire path as folder name and storing already visited paths in a HashMap + appending a number to the file name for duplicates.

add fn make_contiguous to VecDeque

Adds the following method to VecDeque:

```rust
pub fn make_contiguous(&mut self) -> &mut [T];
```

Taken from https://github.com/rust-lang/rust/pull/69400, after a suggestion by @CryZe https://github.com/rust-lang/rust/pull/69400#issuecomment-590216089

I am in favor of merging this instead of https://github.com/rust-lang/rust/pull/69400.

Rollup of 9 pull requests

Successful merges:

 - #69784 (Optimize strip_prefix and strip_suffix with str patterns)
 - #70548 (Add long error code for error E0226)
 - #70555 (resolve, `try_resolve_as_non_binding`: use `delay_span_bug` due to parser recovery)
 - #70561 (remove obsolete comment)
 - #70562 (infer array len from pattern)
 - #70585 (std: Fix over-aligned allocations on wasm32-wasi)
 - #70587 (Add `Rust` to the code snippet)
 - #70588 (Fix incorrect documentation for `str::{split_at, split_at_mut}`)
 - #70613 (more clippy fixes)

Failed merges:

r? @ghost

more clippy fixes

* use is_empty() instead of len comparison (clippy::len_zero)
* use if let instead of while let loop that never loops (clippy::never_loop)
* remove redundant returns (clippy::needless_return)
* remove redundant closures (clippy::redundant_closure)
* use if let instead of match and wildcard pattern (clippy::single_match)
* don't repeat field names redundantly (clippy::redundant_field_names)

r? @Centril

Fix incorrect documentation for `str::{split_at, split_at_mut}`

The documentation for each method currently states:

> Panics if `mid` is not on a UTF-8 code point boundary, or if it is beyond the last code point of the string slice.

However, this is not consistent with the real behavior, or that of the corresponding methods for `[T]` slices. A comment inside each of the `str` methods states:

> is_char_boundary checks that the index is in [0, .len()]

That is what I would expect the behavior to be, and in fact this seems to be the real behavior. For example ([playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=8e03dcc209d4dd176df2297523f9fee1)):

```rust
fn main() {
    // Prints ("abc", "") and doesn't panic
    println!("{:?}", "abc".split_at(3));
}
```

In this case, I would interpret "the last code point of the string slice" to mean the byte at index 2 in UTF-8. However, it is possible to pass an index of 3, which is definitely "beyond the last code point of the string slice".

I think that this is much clearer, but feel free to bikeshed.

Add `Rust` to the code snippet

Adds `Rust` to the snippet where the code causing the ICE should be placed, so github can render it as Rust code rather than plain code.

std: Fix over-aligned allocations on wasm32-wasi

The wasm32-wasi target delegates its malloc implementation to the
functions in wasi-libc, but the invocation of `aligned_alloc` was
incorrect by passing the number of bytes requested first rather than the
alignment. This commit swaps the order of these two arguments to ensure
that we allocate over-aligned memory correctly.

infer array len from pattern

closes #70529

This still errors in the following case

```rust
#![feature(const_generics)]
fn arr<const N: usize>() -> [u8; N] {
    todo!()
}

fn main() {
    match arr() {
        [5, ..] => (),
        //~^ ERROR cannot pattern-match on an array without a fixed length
        [_, _] => (),
    }
}
```
Considering that this should be rare and is harder to implement I would merge this PR without *fixing* the above.

remove obsolete comment

Made obsolete by b5e35b12

resolve, `try_resolve_as_non_binding`: use `delay_span_bug` due to parser recovery

Fixes #70549

r? @petrochenkov

Add long error code for error E0226

Added a long description message for error E0226, which previously did not exist.
As requested in issue #61137

r? @GuillaumeGomez

Optimize strip_prefix and strip_suffix with str patterns

As mentioned in https://github.com/rust-lang/rust/issues/67302#issuecomment-585639226.
I'm not sure whether adding these methods to `Pattern` is desirable—but they have default implementations so the change is backwards compatible. Plus it seems like they're slated for wholesale replacement soon anyway? #56345

----

Constructing a Searcher in strip_prefix and strip_suffix is
unnecessarily slow when the pattern is a fixed-length string. Add
strip_prefix and strip_suffix methods to the Pattern trait, and add
optimized implementations of these methods in the str implementation.
The old implementation is retained as the default for these methods.

use is_empty() instead of len comparison (clippy::len_zero)
use if let instead of while let loop that never loops (clippy::never_loop)
remove redundant returns (clippy::needless_return)
remove redundant closures (clippy::redundant_closure)
use if let instead of match and wildcard pattern (clippy::single_match)
don't repeat field names redundantly (clippy::redundant_field_names)

The wasm32-wasi target delegates its malloc implementation to the
functions in wasi-libc, but the invocation of `aligned_alloc` was
incorrect by passing the number of bytes requested first rather than the
alignment. This commit swaps the order of these two arguments to ensure
that we allocate over-aligned memory correctly.

submodules: update clippy from 70b93aab to e170c849

Changes:
````
rustup  https://github.com/rust-lang/rust/pull/70536
Rustup to https://github.com/rust-lang/rust/pull/70449
readme: move "how to run single lint" instructions to "Allowing/denying lints" section.
git attribute macros not allowed in submodules
Deprecate REPLACE_CONSTS lint
Bump itertools
````

Fixes #70554

Co-Authored-By: NMazdak Farrokhzad <twingoow@gmail.com>

Changes:
````
rustup  https://github.com/rust-lang/rust/pull/70536
Rustup to https://github.com/rust-lang/rust/pull/70449
readme: move "how to run single lint" instructions to "Allowing/denying lints" section.
git attribute macros not allowed in submodules
Deprecate REPLACE_CONSTS lint
Bump itertools
````

Fixes #70554

Constructing a Searcher in strip_prefix and strip_suffix is
unnecessarily slow when the pattern is a fixed-length string. Add
strip_prefix and strip_suffix methods to the Pattern trait, and add
optimized implementations of these methods in the str implementation.
The old implementation is retained as the default for these methods.

Rollup of 4 pull requests

Successful merges:

 - #70479 (avoid creating unnecessary reference in Windows Env iterator)
 - #70546 (Polonius: update to 0.12.1, fix more move errors false positives, update test expectations)
 - #70559 (fix BTreeMap test compilation with Miri)
 - #70567 (Fix broken link in README)

Failed merges:

r? @ghost

Fix broken link in README

Fix broken link to `rustc-dev-guide` section for `codegen`

fix BTreeMap test compilation with Miri

This got broken by https://github.com/rust-lang/rust/pull/70506

Polonius: update to 0.12.1, fix more move errors false positives, update test expectations

This PR:
- updates `polonius-engine` to version 0.12.1 to fix some move errors false positives
- fixes a fact generation mistake creating the other move errors false positives
- updates the test expectations for the polonius compare-mode so that all (minus the 2 OOMs) ui tests pass again (matching the [analysis doc](https://hackmd.io/CjYB0fs4Q9CweyeTdKWyEg?view) starting at case 34)

In my opinion, this is safe to rollup.

r? @nikomatsakis

avoid creating unnecessary reference in Windows Env iterator

Discovered in https://github.com/rust-lang/miri/pull/1225: the Windows `Env` iterator violates Stacked Borrows by creating an `&u16`, turning it into a raw pointer, and then accessing memory outside the range of that type.

There is no need to create a reference here in the first place, so the fix is trivial.
Cc @JOE1994
Cc https://github.com/rust-lang/unsafe-code-guidelines/issues/134