Implement the va args in codegen for AAPCS, this will be used as the
default va_args implementation for AArch64 rather than the va_args
llvm-ir as it currently is.

Copyright (c) 2020, Arm Limited.

This makes extract_lldb_version has the same version type like
extract_gdb_version.

This is technically a breaking change for rustc-dev users.
But note that rustc-dev is a nightly component.

This commit refactors intra-doc link error reporting to deduplicate code
and decouple error construction from the type of error. This greatly
improves flexibility at each error construction site, while reducing the
complexity of the diagnostic creation.

This commit also rewords the diagnostics for clarity and style:

- Diagnostics should not end in periods.
- It's unnecessary to say "ignoring it". Since this is a warning by
  default, it's already clear that the link is ignored.

Also the alignment should only be done on general register types as
per the AAPCS so fixed that issue.

Copyright (c) 2020, Arm Limited.

va_args implementation for AAPCS.

Implement the va args in codegen for AAPCS, this will be used as the
default va_args implementation for AArch64 rather than the va_args
llvm-ir as it currently is.

This should fix the following issues:
rust-lang#56475
rust-lang#72579

…atsakis

Stabilize control-flow-guard codegen option

This is the stabilization PR discussed in rust-lang#68793. It converts the `-Z control-flow-guard` debugging option into a codegen option (`-C control-flow-guard`), and changes the associated tests.

compiletest: Rewrite extract_*_version functions

This makes extract_lldb_version has the same version type like
extract_gdb_version.

small coherence cleanup

r? @eddyb

refactor and reword intra-doc link errors

This commit refactors intra-doc link error reporting to deduplicate code
and decouple error construction from the type of error. This greatly
improves flexibility at each error construction site, while reducing the
complexity of the diagnostic creation.

This commit also rewords the diagnostics for clarity and style:

- Diagnostics should not end in periods.
- It's unnecessary to say "ignoring it". Since this is a warning by
  default, it's already clear that the link is ignored.

Apply rust-lang#66379 to `*mut T` `as_ref`

rust-lang#66379 changed the documentation of `as_ref` on the type `*const T` and `as_mut` on the type `*mut T`, but it missed making that same change for `as_ref` on the type `*mut T`.

…dures-links, r=Mark-Simulacrum

Use forge links for prioritization procedure

r? @Mark-Simulacrum

cc @rust-lang/wg-prioritization

Update books

## reference

5 commits in 0ea7bc494f1289234d8800bb9185021e0ad946f0..b329ce37424874ad4db94f829a55807c6e21d2cb
2020-07-02 15:33:04 -0700 to 2020-07-20 08:54:08 -0700
- this '*' is unnecessary, and reduces readability (rust-lang/reference#853)
- Tiny typo fix (rust-lang/reference#849)
- Update const eval chapter to latest changes (rust-lang/reference#842)
- Document #[track_caller]. (rust-lang/reference#742)
- Document shebang restriction. (rust-lang/reference#823)

## book

2 commits in 84a31397b34f9d405df44f2899ff17a4828dba18..a914f2c7e5cdb771fa465de142381a51c53b580e
2020-07-04 10:50:18 -0500 to 2020-07-21 09:20:05 -0500
- Change misleading wording (rust-lang/book#2399)
- Improve wording to include Windows versions (rust-lang/book#2395)

## edition-guide

3 commits in 82bec5877c77cfad530ca11095db4456d757f668..bd6e4a9f59c5c1545f572266af77f5c7a5bad6d1
2020-06-03 08:56:02 -0500 to 2020-07-12 17:37:08 -0500
- update guide for 1.36 and 1.37 (rust-lang/edition-guide#217)
- Add contents for Rust 1.35 (rust-lang/edition-guide#216)
- update edition guide for Rust 1.34 (rust-lang/edition-guide#215)

…anishearth

Fix tooltip position if the documentation starts with a code block

Fixes rust-lang#74321.

Before:

![before](https://user-images.githubusercontent.com/3050060/88188970-cf842400-cc38-11ea-839b-37e41656837d.png)

After:

![after](https://user-images.githubusercontent.com/3050060/88188981-d3b04180-cc38-11ea-8194-713ffe640d3a.png)

And in case there is text, it is not being applied:

![after-witness](https://user-images.githubusercontent.com/3050060/88189009-ddd24000-cc38-11ea-9f0a-61dfd0a0cbd0.png)

And on mobile it isn't needed so it's not "activated":

![Screenshot from 2020-07-22 17-17-43](https://user-images.githubusercontent.com/3050060/88194698-65bb4880-cc3f-11ea-8513-0043ccca8cfc.png)

r? @rust-lang/rustdoc