Fix rust-lang#86756

The `large_assignments` lints detects moves over specified limit.  The
limit is configured through `move_size_limit = "N"` attribute placed at
the root of a crate. When attribute is absent, the lint is disabled.

Make it possible to enable the lint without making any changes to the
source code, through a new flag `-Zmove-size-limit=N`.  For example, to
detect moves exceeding 1023 bytes in a cargo crate, including all
dependencies one could use:

```
$ env RUSTFLAGS=-Zmove-size-limit=1024 cargo build -vv
```

VxWorks does not provide glibc, but we still need to test rustc on
VxWorks.

Add flag to configure `large_assignments` lint

The `large_assignments` lints detects moves over specified limit.  The
limit is configured through `move_size_limit = "N"` attribute placed at
the root of a crate. When attribute is absent, the lint is disabled.

Make it possible to enable the lint without making any changes to the
source code, through a new flag `-Zmove-size-limit=N`.  For example, to
detect moves exceeding 1023 bytes in a cargo crate, including all
dependencies one could use:

```
$ env RUSTFLAGS=-Zmove-size-limit=1024 cargo build -vv
```

Lint tracking issue rust-lang#83518.

Avoid ICE on type error recovery

Fix rust-lang#86756

Update VxWork's UNIX support

1. VxWorks does not provide glibc
2. VxWorks does provide `sigemptyset` and `sigaddset`

Note: these changes are concurrent to [this PR](rust-lang/libc#2295) in libc.

get rid of NoMirFor error variant

The only place where we throw that error, it is very quickly caught again and turned into a different error. So raise that other error immediately.

macos current_exe using directly libc instead.

fix typo: whenver -> whenever

Fix a typo in a comment in RefCell: "whenver" -> "whenever".

Add long explanation for E0544.

Helps with rust-lang#61137

Remove ASCII fast path from `rustc_lexer::{is_id_continue, is_id_start}`

`unicode_xid` now has a fast path built-in: unicode-rs/unicode-xid@122b387

Update cargo

8 commits in cebef2951ee69617852844894164b54ed478a7da..d21c22870e58499d6c31f1bef3bf1255eb021666
2021-07-22 13:01:52 +0000 to 2021-07-26 20:23:21 +0000
- Fix version string. (rust-lang/cargo#9727)
- Allow publishing from workspace root. (rust-lang/cargo#9559)
- Better msg for wrong position (rust-lang/cargo#9723)
- Stabilize the rustc-link-arg option (rust-lang/cargo#9557)
- Warning when using features in replace (rust-lang/cargo#9681)
- Refactor if let chains to matches! macro (rust-lang/cargo#9721)
- Weather is not nice today.. (rust-lang/cargo#9720)
- Update should_use_metadata function (rust-lang/cargo#9653)

Update books

## nomicon

1 commits in 7a13537f96af4b9b8e3ea296d6e5c3c7ab72ce9f..f51734eb5566c826b471977747ea3d7d6915bbe9
2021-07-05 23:34:47 -0400 to 2021-07-23 18:24:35 +0900
- Add cloning example for dot operator behaviour (rust-lang/nomicon#292)

## reference

3 commits in 82d75cf423e4a7824fb36e73ccb18519d6900610..3b7be075af5d6e402a18efff672a8a265b4596fd
2021-07-15 06:49:08 -0700 to 2021-07-26 13:20:11 -0700
- Fix typos + grammar (rust-lang/reference#1037)
- Expand on Unicode identifiers. (rust-lang/reference#1022)
- Remove incorrect apostrophe (rust-lang/reference#1076)

## book

17 commits in eac55314210519238652f12b30fec9daea61f7fe..a07036f864b37896b31eb996cd7aedb489f69a1f
2021-07-19 11:08:01 -0400 to 2021-07-26 20:19:46 -0400
- Set expectations a bit more realistically
- Snapshot of chapter 4 for nostarch
- A few small wording tweaks in ch 4
- Clarify that it's not stack/heap exactly that matters for copy/non copy, fixes rust-lang/book#2799
- Clarify a detail around move. Fixes rust-lang/book#2413.
- Clarify places that changed because of NLL. Fixes rust-lang/book#1939.
- nostarch ch3
- Small edits to chapter 3
-  (rust-lang/book#2797)
- Update ch03-03-how-functions-work.md: Pervasive -> Prevalent. (rust-lang/book#2796)
- Address loop labels and continue. Fixes rust-lang/book#1392.
- Clarify behavior of integer division. Fixes rust-lang/book#2248.
- Demonstrate how scope interacts with shadowing
- Add another cross-reference to the new unit type introduction
- Introduce the unit type with tuples. Fixes rust-lang/book#1933.
- Reword sentence to not have numbers separated only by a comma
- Link directly to other installation page. Fixes rust-lang/book#1609

## rust-by-example

1 commits in 1db6bb483cc87ad3b424d9aba764fe622960a1be..0dc9cd4e89f00cb5230f120e1a083916386e422b
2021-07-15 06:17:42 -0300 to 2021-07-23 09:14:27 -0300
- Grammatical mistake: Comparison as ... as the (rust-lang/rust-by-example#1453)

## rustc-dev-guide

2 commits in 93422c21baca585dc88357ec886a48f6ddc7d665..09343d6f921d2a07c66f8c41ec3d65bf1fa52556
2021-07-13 12:45:58 -0400 to 2021-07-26 00:37:28 +0200
- Fix typo in building/bootstrapping.md (rust-lang/rustc-dev-guide#1175)
- Link directly to stabilization report comments (rust-lang/rustc-dev-guide#1173)

## edition-guide

4 commits in af696ce8ea526445590ae0ca66a8128d2a95a69a..3710b0cae783d0bcd2b42452a63b081473f5970a
2021-07-20 11:38:03 -0400 to 2021-07-26 11:34:46 -0700
- Add more consistent headings and add a migration section to reserving-syntax (rust-lang/edition-guide#263)
- reserving-syntax.md: Expand and add detail (rust-lang/edition-guide#249)
- Fix typo in or-patterns section (rust-lang/edition-guide#262)
- Fix typo (rust-lang/edition-guide#261)