Use the right TLS model for CloudABI.

CloudABI doesn't do dynamic linking. For this reason, there is no need
to handle any other TLS model than local-exec. CloudABI's C library
doesn't provide a __tls_get_addr() function to do Dynamic TLS.

By forcing local-exec to be used here, we ensure that we don't generate
function calls to __tls_get_addr().

Disable printing of error message on file descriptor 2 on CloudABI.

As CloudABI is a capability-based runtime environment, file descriptors
are the mechanism that grants rights to a process. These file
descriptors may be passed into processes on startup using a utility
called cloudabi-run. Unlike the POSIX shell, cloudabi-run does not
follow the UNIX model where file descriptors 0, 1 and 2 represent stdin,
stdout and stderr. There can be arbitrary many (or few) file descriptors
that can be provided. For this reason, CloudABI's C library also doesn't
define STD*_FILENO. liblibc should also not declare these.

Disable the code in liballoc_system that tries to print error messages
over file descriptor 2. For now, let's keep this function quiet. We'll
see if we can think of some other way to log this in the future.

Correct a few stability attributes

* The extra impls for `ManuallyDrop` were added in #44310 which was only stabilised in 1.22.0.
* The impls for `SliceIndex` were stabilised in #43373 but as `RangeInclusive` and `RangeToInclusive` are still unstable the impls should remain unstable.
* The `From` impls for atomic integers were added in #45610 but most atomic integers are still unstable.
* The `shared_from_slice2` impls were added in #45990 but they won't be stable until 1.24.0.
* The `Mutex` and `RwLock` impls were added in #46082 but won't be stable until 1.24.0.

Allow non-alphabetic underscores in camel case

Certain identifiers, such as `X86_64`, cannot currently be unambiguously represented in camel case (`X8664`, `X86_64`, `X8_664`, etc. are all transformed to the same identifier). This change relaxes the rules so that underscores are permitted between two non-alphabetic characters under `#[forbid(non_camel_case_types)]`. Fixes #34633 and fixes #41621.

[needs perf run] Try to improve LLVM pass ordering

Fixes #45466

Generate code for unused const- and inline-fns if -Clink-dead-code is specified.

Fixes https://github.com/rust-lang/rust/issues/46467.

r? @alexcrichton

Force appropriate extension when converting from int to ptr #43291

Fixes #43291.

Looking for feedback if I've missed something and/or need to add more tests.

@EddyB @retep998 @nagisa @oli-obk

Reword reason for move note

On move errors, when encountering an enum variant, be more ambiguous and do not refer to the type on the cause note, to avoid referring to `(maybe as std::prelude::v1::Some).0`, and instead refer to `the value`.

Sidesteps part of the problem with #41962:

```
error[E0382]: use of partially moved value: `maybe`
 --> file.rs:5:30
  |
5 |         if let Some(thing) = maybe {
  |                     -----    ^^^^^ value used here after move
  |                     |
  |                     value moved here
  = note: move occurs because the value has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait

error[E0382]: use of moved value: `(maybe as std::prelude::v1::Some).0`
 --> file.rs:5:21
  |
5 |         if let Some(thing) = maybe {
  |                     ^^^^^ value moved here in previous iteration of loop
  = note: move occurs because the value has type `std::vec::Vec<bool>`, which does not implement the `Copy` trait

error: aborting due to 2 previous errors
```

Previous discussion: #44360

r? @arielb1

Limit style lint to non-synthetic generic params

Fix https://github.com/rust-lang/rust/issues/46959

r? @nikomatsakis

NLL fixes

First, introduce pre-statement effects to dataflow to fix #46875. Edge dataflow effects might make that redundant, but I'm not sure of the best way to integrate them with liveness etc., and if this is a hack, this is one of the cleanest hacks I've seen.

And I want a small fix to avoid the torrent of bug reports.

Second, fix linking of projections to fix #46974

r? @pnkfelix

First cut at getting some part of the test suite working for CloudABI

I am currently working on creating a Docker container for automated CI for CloudABI. Here are some of the trivial changes that need to land to make tests pass.

Requested by: kennytm

CStore switch FxHashMap to IndexVec

This is a first attempt to fix #46876.

Rollup of 9 pull requests

- Successful merges: #47104, #47107, #47113, #47117, #47118, #47121, #47125, #47134, #47145
- Failed merges:

Document when LineWriter flushes; document errors for into_inner.

Fixes https://github.com/rust-lang/rust/issues/42468.

Defocus search bar in rustdoc pages

rust-lang/rfcs#2265

Mention SliceConcatExt's stability in its docs

Just saw someone in IRC mention there being no stable way to join string slices! It isn't entirely clear from the rust documentation that `SliceConcatExt` is usable. While this is mentioned in https://doc.rust-lang.org/std/prelude/, the trait has nothing to indicate that it's currently usable if found via a documentation search.

The wording on this could probably be improved, but I'm hoping its better than nothing.

Fix panic condition docs for Vec::insert.

Fixes https://github.com/rust-lang/rust/issues/47065.

memchr: fix variable name in docstrings

upstream BurntSushi/rust-memchr#24

r=BurntSushi

[unstable book] remove duplicate entries

if a unstable feature is a language feature, it shouldn't also have a library feature stub generated

Minor cleanup for slice::Chunks and ChunksMut

This only renames the `size` field to `chunk_size` in one of them for consistency, and changes an assertion to check for != 0 instead of > 0.

Fix typo

I am assuming that there was once something else you could do and somebody forgot to remove "either". Is that correct?

Delay panic from incoherent drop implementation

Closes #41974

Move static code outside of unciode.py.

This script in libstd_unicode is a mess and also contains code that shouldn't be output by a script, and instead just put in modules. So, this change does that.

Only bump error count when we are sure that the diagnostic is not a repetition

This ensures that if we emit the same diagnostic twice, the error count will
match the real number of errors shown to the user.

Fixes #42106

This is a followup of https://github.com/rust-lang/rust/pull/45603 as stated in https://github.com/rust-lang/rust/issues/42106#issuecomment-345218473.

This program, for example:

```rust
fn do_something<T>(collection: &mut Vec<T>) {
    let _a = &collection;
    collection.swap(1, 2);
}

fn main() {}
```

without this patch, produces:

```
error[E0502]: cannot borrow `*collection` as mutable because `collection` is also borrowed as immutable
  --> $DIR/issue-42106.rs:13:5
   |
12 |     let _a = &collection;
   |               ---------- immutable borrow occurs here
13 |     collection.swap(1, 2); //~ ERROR also borrowed as immutable
   |     ^^^^^^^^^^ mutable borrow occurs here
14 | }
   | - immutable borrow ends here

error: aborting due to 2 previous errors
```

The number of errors do not match the diagnostics reported. This PR fixes this problem. The output is now in this case:

```
error[E0502]: cannot borrow `*collection` as mutable because `collection` is also borrowed as immutable
  --> $DIR/issue-42106.rs:13:5
   |
12 |     let _a = &collection;
   |               ---------- immutable borrow occurs here
13 |     collection.swap(1, 2); //~ ERROR also borrowed as immutable
   |     ^^^^^^^^^^ mutable borrow occurs here
14 | }
   | - immutable borrow ends here

error: aborting due to previous error
```

Also, some other tests outputs have been adapted because their count didn't really match the number of diagnostics reported.

As an aside, an outdated comment has been removed (`Handler::cancel` will only call to the `Diagnostic::cancel` method and will not decrease the count of errors).

All tests are passing with this PR (`x.py test` is successful).

This ensures that if we emit the same diagnostic twice, the error count will
match the real number of errors shown to the user.

Fixes #42106

Fixes https://github.com/rust-lang/rust/issues/42468.

Fixed intentaion (tabs -> spaces)
Added trailing newline

Escape now removes focus from the search bar

Due to the disable-cloudabi tags being added to the source files, the
expected output of the compiler is altered slightly.

Delay panic for aliasing violation for static items.

Closes #46604

CloudABI doesn't make any distinction between TTYs and ordinary pipes.
While there, remove the redundant implementation used by Redox. It can
use the same stub function.