* Rebuild sanitizers runtimes when LLVM submodule commit changes.
* When rebuilding LLVM / sanitizers, remove the stamp file before
  starting the build process to invalidate previous build output.

It was unused.

Regions in TypeckTables will be erased, so are unusable for error
reporting.

Also skip duplicated region solving entirely with `-Zborrowck=mir`.

typo fix + markdown fix for consistency

…henkov

Make macro metavars respect (non-)hygiene

This makes them more consistent with other name resolution while not breaking any code on crater.

…komatsakis

Erase regions in writeback

Regions in `TypeckTables` (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with `-Zborrowck=mir`.

cc rust-lang#68261
r? @nikomatsakis

Move tidy check to mingw-check

Fixes rust-lang#69613

…r=Mark-Simulacrum

bootstrap: Use hash to determine if sanitizers needs to be rebuilt

* Rebuild sanitizers runtimes when LLVM submodule commit changes.
* When rebuilding LLVM / sanitizers, remove the stamp file before
  starting the build process to invalidate previous build output.

Expansion-driven outline module parsing

After this PR, the parser will not do any conditional compilation or loading of external module files when `mod foo;` is encountered. Instead, the parser only leaves `mod foo;` in place in the AST, with no items filled in. Expansion later kicks in and will load the actual files and do the parsing. This entails that the following is now valid:

```rust
#[cfg(FALSE)]
mod foo {
    mod bar {
        mod baz; // `foo/bar/baz.rs` doesn't exist, but no error!
    }
}
```

Fixes rust-lang#64197.

r? @petrochenkov

implement zeroed and uninitialized with MaybeUninit

This is the second attempt of doing such a change (first PR: rust-lang#62150). The last change [got reverted](rust-lang#63343) because it [caused](rust-lang#62825) some [issues](rust-lang#52898 (comment)) in [code that incorrectly used these functions](AltF02/x11-rs#99).

Since then, the [problematic code has been fixed](AltF02/x11-rs#101), and rustc [gained a lint](rust-lang#63346) that is able to detect many misuses of these functions statically and a [dynamic check that panics](rust-lang#66059) instead of causing UB for some incorrect uses.

Fixes rust-lang#62825

Cosmetic fixes in documentation

typo fix + markdown fix for consistency

Update books

## reference

4 commits in 559e09c..e2f11fe
2020-03-02 01:17:14 +0100 to 2020-03-10 06:59:24 +0100
- Update rustc-guide to rustc-dev-guide (rust-lang/reference#777)
- Fix expression and statement grammar. (rust-lang/reference#776)
- Fix grammar for tuple struct patterns. (rust-lang/reference#775)
- A typo? (rust-lang/reference#770)

## rust-by-example

3 commits in db57f899ea2a56a544c8d280cbf033438666273d..cb369ae95ca36b841960182d26f6d5d9b2e3cc18
2020-02-18 17:46:46 -0300 to 2020-03-14 12:13:22 -0500
- Use rust-lang/rust linkchecker on CI. (rust-lang/rust-by-example#1310)
- Rewrite freeze.md (rust-lang/rust-by-example#1314)
- Clarify type suffixing with example (rust-lang/rust-by-example#1312)

## embedded-book

2 commits in b81ffb7a6f4c5aaed92786e770e99db116aa4ebd..d22a9c487c78095afc4584f1d9b4ec43529d713c
2020-02-27 08:06:04 +0000 to 2020-03-04 09:46:30 +0000
- Updated documentation on profile-overrides  (rust-embedded/book#230)
- Update information on Cargo `profile-overrides`  (rust-embedded/book#229)