Rollup of 5 pull requests (all of which changes `src/ci/docker`)

Successful merges:

 - #58986 ([CI] Update binutils for powerpc64 and powerpc64le)
 - #59038 (Track embedded-book in the toolstate)
 - #59055 (CI: Set job names.)
 - #59253 (Calculate Docker cache hash precisely from Dockerfile's dependencies)
 - #59257 (Update CI configuration for building Redox libraries)

Failed merges:

r? @ghost

Update CI configuration for building Redox libraries

This fixes https://github.com/rust-lang/rust/issues/59254

Calculate Docker cache hash precisely from Dockerfile's dependencies

#58549 changed the Docker cache calculation to include every file under `src/ci/docker`, so that when files under `dist-x86_64-linux` is changed, its dependent image `dist-i686-linux` will also be rebuilt.

However, this ultraconservative solution caused the `dist-i686-linux` to be rebuilt every time an irrelevant Dockerfile (e.g. the PowerPC ones) is changed, which increases the building time beyond 3 hours and forcing a spurious but expected failure.

This commit instead parses the Dockerfile itself and look for the actual dependencies. The scripts needs to be copied into the Docker image, which must be done with the COPY command, so we just need to find all lines with a COPY command and add the source file into the hash calculator.

Note: this script only handles single-lined COPY command in the form `COPY src1 src2 src3 dst`, since these are the only variant used inside this repository.

CI: Set job names.

This should make it easier to identify what each job is doing when looking at the Travis or Appveyor UI.

- Set `name` for each job in Travis.
- Move `CI_JOB_NAME` to the front in Appveyor so that it appears first in the UI.

Track embedded-book in the toolstate

The embedded book was tested in the tools job but the test result was never published. This PR adds maintainer information of embedded-book. This PR also requires the next update to embedded-book to pass the all tests, currently its state is test-fail.

rust-lang-nursery/rust-toolstate#10 should be merged before this PR.

[CI] Update binutils for powerpc64 and powerpc64le

Cargo powerpc64 and powerpc64le are seeing `SIGILL` crashes in openssl,
which was found to be a linking problem, fixed by newer binutils. See
<https://github.com/rust-lang/rust/issues/57345#issuecomment-462094555>

For powerpc64 we're using crosstool-ng, which doesn't offer a newer
binutils version, but we can just compile it separately. On powerpc64le
we're already building binutils. Both are now updated to binutils 2.32.

Closes rust-lang/cargo#6320
Closes rust-lang/rust#57345
Closes rust-lang/rustup.rs#1620

r? @alexcrichton

Move libtest out of rust-lang/rust

This is a first step towards a number of goals explained in this internals post: https://internals.rust-lang.org/t/a-path-forward-towards-re-usable-libtest-functionality-custom-test-frameworks-and-a-stable-bench-macro

This PR does not fully remove libtest from rust-lang/rust, we keep a shim that imports and re-exports the external libtest, and adds the proc_macro dependency, etc.

r? @alexcrichton

cc @djrenren @petrochenkov

Rollup of 11 pull requests

Successful merges:

 - #56348 (Add todo!() macro)
 - #57729 (extra testing of how NLL handles wildcard type `_`)
 - #57847 (dbg!() without parameters)
 - #58778 (Implement ExactSizeIterator for ToLowercase and ToUppercase)
 - #58812 (Clarify distinction between floor() and trunc())
 - #58939 (Fix a tiny error in documentation of std::pin.)
 - #59116 (Be more discerning on when to attempt suggesting a comma in a macro invocation)
 - #59252 (add self to mailmap)
 - #59275 (Replaced self-reflective explicit types with clearer `Self` or `Self::…` in stdlib docs)
 - #59280 (Stabilize refcell_map_split feature)
 - #59290 (Run branch cleanup after copy prop)

Failed merges:

r? @ghost

Run branch cleanup after copy prop

This is preliminary work for https://github.com/rust-lang/rust/pull/59288#issuecomment-474277172 which gets rid of `if` in the HIR.

cc @rust-lang/wg-mir-opt 	@Centril

Stabilize refcell_map_split feature

Closes #51476.

Replaced self-reflective explicit types with clearer `Self` or `Self::…` in stdlib docs

Many docs examples use explicit types instead of the semantically more clear `Self`/`Self::…` aliases.

By using the latter it's clear that the value's type depends on either `Self`, or an associated type of `Self`, instead of some constant type. It's also more consistent (and I'd argue correct), as the current docs aren't really consistent in this, as can be seen from the diff.

This is a best effort PR, as I was basically going through the docs manually, looking for offending examples. I'm sure I missed a few. Gotta start somewhere.

add self to mailmap

Be more discerning on when to attempt suggesting a comma in a macro invocation

Fix #58796.

Fix a tiny error in documentation of std::pin.

`new_unmoved` must be `mut` for passing to `std::mem::swap`.

Clarify distinction between floor() and trunc()

`floor()` rounds towards `-INF`, `trunc()` rounds towards 0.
This PR clarifies this in the examples.

Implement ExactSizeIterator for ToLowercase and ToUppercase

dbg!() without parameters

Fixes #57845.

Rollup merge of #57729 - pnkfelix:issue-55748-pat-types-are-constraints-on-bindings-too, r=nikomatsakis

extra testing of how NLL handles wildcard type `_`

test that wildcard type `_` is not duplicated by `type Foo<X> = (X, X);` and potentially instantiated at different types when used in type ascriptions in let bindings.

(NLL's handling of this for the type ascription *expression form* is currently broken, or at least differs from what AST-borrowck does. I'll file a separate bug about that. Its not something critical to address since that expression is guarded by `#![feature(type_ascription)]`.)

cc #55748

Add todo!() macro

The primary use-case of `todo!()` macro is to be a much easier to type
alternative to `unimplemented!()` macro.

EDIT: hide unpopular proposal about re-purposing unimplemented

<details>
However, instead of just replacing `unimplemented!()`, it gives it a
more nuanced meaning: a thing which is intentionally left
unimplemented and which should not be called at runtime. Usually,
you'd like to prevent such cases statically, but sometimes you, for
example, have to implement a trait only some methods of which are
applicable. There are examples in the wild of code doing this thing,
and in this case, the current message of `unimplemented`, "not *yet*
implemented" is slightly misleading.

With the addition of TODO, you have three nuanced choices for a
`!`-returning macro (in addition to a good-old panic we all love):

  * todo!()
  * unreachable!()
  * unimplemented!()

Here's a rough guideline what each one means:

- `todo`: use it during development, as a "hole" or placeholder. It
  might be a good idea to add a pre-commit hook which checks that
  `todo` is not accidentally committed.

- `unreachable!()`: use it when your code can statically guarantee
  that some situation can not happen. If you use a library and hit
  `unreachable!()` in the library's code, it's definitely a bug in the
  library. It's OK to have `unreachable!()` in the code base,
  although, if possible, it's better to replace it with
  compiler-verified exhaustive checks.

- `unimplemented!()`: use it when the type checker forces you to
  handle some situation, but there's a contract that a callee must not
  actually call the code. If you use a library and hit
  `unimplemented!()`, it's probably a bug in your code, though
  it *could* be a bug in the library (or library docs) as well. It is
  ok-ish to see an `unimplemented!()` in real code, but it usually
  signifies a clunky, eyebrow-rising API.
</details>

This functionality was added in 1.35.0, not 1.34.0.

Update clippy

Fixes https://github.com/rust-lang/rust/issues/59218

cc @Xanewok

- Closes #51476

Define queries using a proc macro

cc @rust-lang/compiler

The use-case of `todo!()` macro is to be a much easier to type
alternative to `unimplemented!()` macro.