make `everybody_loops` preserve item declarations

First half of https://github.com/rust-lang/rust/issues/52545.

`everybody_loops` is used by rustdoc to ensure we don't contain erroneous references to platform APIs if one of its uses is pulled in by `#[doc(cfg)]`. However, you can also implement traits for public types inside of functions. This is used by Diesel (probably others, but they were the example that was reported) to get around a recent macro hygiene fix, which has caused their crate to fail to document. While this won't make the traits show up in documentation (that step comes later), it will at least allow files to be generated.

data_structures: make TinyList more readable and optimize remove(_)

also add benchmarks

Before:

```
test tiny_list::test::bench_insert_empty             ... bench:           1 ns/iter (+/- 0)
test tiny_list::test::bench_insert_one               ... bench:          16 ns/iter (+/- 0)
test tiny_list::test::bench_remove_empty             ... bench:           2 ns/iter (+/- 0)
test tiny_list::test::bench_remove_one               ... bench:           6 ns/iter (+/- 0)
test tiny_list::test::bench_remove_unknown           ... bench:           4 ns/iter (+/- 0)
```

After:

```
test tiny_list::test::bench_insert_empty             ... bench:           1 ns/iter (+/- 0)
test tiny_list::test::bench_insert_one               ... bench:          16 ns/iter (+/- 0)
test tiny_list::test::bench_remove_empty             ... bench:           0 ns/iter (+/- 0)
test tiny_list::test::bench_remove_one               ... bench:           3 ns/iter (+/- 0)
test tiny_list::test::bench_remove_unknown           ... bench:           2 ns/iter (+/- 0)
```

rustdoc: refactor how passes are structured, and turn intra-doc-link collection into a pass

This builds on https://github.com/rust-lang/rust/pull/52751 and should not be merged until that finally finishes the bors queue

Part 2 of my passes refactor. This introduces the concept of an "early pass", which is run right before exiting the compiler context. This is important for passes that may want to ask the compiler about things. For example, i took out the intra-doc-link collection and turned it into a early pass. I also made the `strip-hidden`, `strip-private` and `strip-priv-imports` passes occur as early passes, so that intra-doc-link collection wouldn't run on docs that weren't getting printed.

Fixes https://github.com/rust-lang/rust/issues/51684, technically https://github.com/rust-lang/rust/issues/51468 too but that version of `h2` hits a legit intra-link error after that `>_>`

r? @rust-lang/rustdoc

Update LLVM submodule to 7.0

This commit updates the following submodules to LLVM's [recently branched][1]
7.0 release branch:

* src/llvm
* src/tools/lld
* src/libcompiler_builtins/compiler-rt

[1]: https://lists.llvm.org/pipermail/llvm-dev/2018-August/125004.html

Closes #52970

[NLL] Use smaller spans for errors involving closure captures

Closes #51170
Closes #46599

Error messages involving closures now point to the captured variable/closure args.

r? @pnkfelix

avoid computing liveness for locals that escape into statics

Fixes #52713

I poked at this on the plane and I think it's working -- but I want to do a bit more investigation and double check. The idea is to identify those local variables where the entire value will "escape" into the return -- for them, we don't need to compute liveness, since we know that the outlives relations from the return type will force those regions to be equal to free regions. This should help with html5ever in particular.

- [x] test performance
- [x] verify correctness
- [x] add comments

r? @pnkfelix
cc @lqd

Update cargo to fix Rust 2018 build scripts

This commit updates the following submodules to LLVM's [recently branched][1]
7.0 release branch:

* src/llvm
* src/tools/lld
* src/libcompiler_builtins/compiler-rt

[1]: https://lists.llvm.org/pipermail/llvm-dev/2018-August/125004.html

Closes #52970

Update rustfmt, RLS, Clippy

r? @kennytm

Fixes RLS build and updates RLS and Rustfmt to their 1.0 RCs

rustdoc: clean up generic impls

r? @QuietMisdreavus

Cleanup for librustc::session

Some rather straightforward cleanup. Each commit mostly stands alone.

Rollup of 14 pull requests

Successful merges:

 - #51919 (Provide `{to,from}_{ne,le,be}_bytes` functions on integers)
 - #52940 (Align 6-week cycle check with beta promotion instead of stable release.)
 - #52968 (App-lint-cability)
 - #52969 (rustbuild: fix local_rebuild)
 - #52995 (Remove unnecessary local in await! generator)
 - #52996 (RELEASES.md: fix the `hash_map::Entry::or_default` link)
 - #53001 (privacy: Fix an ICE in `path_is_private_type`)
 - #53003 (Stabilize --color and --error-format options in rustdoc)
 - #53022 (volatile operations docs: clarify that this does not help wrt. concurrency)
 - #53024 (Specify reentrancy gurantees of `Once::call_once`)
 - #53041 (Fix invalid code css rule)
 - #53047 (Make entire row of doc search results clickable)
 - #53050 (Make left column of rustdoc search results narrower)
 - #53062 (Remove redundant field names in structs)

Remove redundant field names in structs

This is a clippy-breaking change.

Make left column of rustdoc search results narrower

To make more room for the description of the item

The description often has useful text that helps disambiguate between search results, but very little of it is shown.

As a side effect, this breaks the alignment between the search results and the "In Return Types" tab, which tends to line up above the description-- up until I started investigating this, I thought "In Names"/"In Parameters"/"In Return Types" were column headers and I just never saw search results that had info for the "In Parameters" middle column! Now, with the two columns of search results each taking up about a half, they look more like tabs than column headers.

Types that are long still wrap and look good-- I made some artificially long types in the following screenshots.

Before screenshot:

<img width="1258" alt="screen shot 2018-08-03 at 8 32 35 pm" src="https://user-images.githubusercontent.com/193874/43670805-56e3b3b4-975e-11e8-9296-600837d03de2.png">

After screenshot:

<img width="1239" alt="screen shot 2018-08-03 at 8 31 17 pm" src="https://user-images.githubusercontent.com/193874/43670810-6591f9ac-975e-11e8-9e12-4ea9ab1e5806.png">

Provide `{to,from}_{ne,le,be}_bytes` functions on integers

If one doesn't view integers as containers of bytes, converting them to
bytes necessarily needs the specfication of encoding.

I think Rust is a language that wants to be explicit. The `to_bytes`
function is basically the opposite of that – it converts an integer into
the native byte representation, but there's no mention (in the function
name) of it being very much platform dependent. Therefore, I think it
would be better to replace that method by three methods, the explicit
`to_ne_bytes` ("native endian") which does the same thing and
`to_{le,be}_bytes` which return the little- resp. big-endian encoding.