Make backtraces work on Windows GNU targets again.

This is done by adding a function that can return a filename
to pass to backtrace_create_state. The filename is obtained in
a safe way by first getting the filename, locking the file so it can't
be moved, and then getting the filename again and making sure it's the same.

See: https://github.com/rust-lang/rust/pull/37359#issuecomment-260123399
Issue: #33985

Note though that this isn't that pretty...

I had to implement a `WideCharToMultiByte` wrapper function to convert to the ANSI code page. This will work better than only allowing ASCII provided that the ANSI code page is set to the user's local language, which is often the case.

Also, please make sure that I didn't break the Unix build.

Fix typos in libsyntax/tokenstream.rs

Don't generate doc if doc comments only filled with 'white' characters

Fixes #39339.

r? @steveklabnik

cc @rust-lang/docs

Perform lifetime elision (more) syntactically, before type-checking.

The *initial* goal of this patch was to remove the (contextual) `&RegionScope` argument passed around `rustc_typeck::astconv` and allow converting arbitrary (syntactic) `hir::Ty` to (semantic) `Ty`.
I've tried to closely match the existing behavior while moving the logic to the earlier `resolve_lifetime` pass, and [the crater report](https://gist.github.com/eddyb/4ac5b8516f87c1bfa2de528ed2b7779a) suggests none of the changes broke real code, but I will try to list everything:

There are few cases in lifetime elision that could trip users up due to "hidden knowledge":
```rust
type StaticStr = &'static str; // hides 'static
trait WithLifetime<'a> {
    type Output; // can hide 'a
}

// This worked because the type of the first argument contains
// 'static, although StaticStr doesn't even have parameters.
fn foo(x: StaticStr) -> &str { x }

// This worked because the compiler resolved the argument type
// to <T as WithLifetime<'a>>::Output which has the hidden 'a.
fn bar<'a, T: WithLifetime<'a>>(_: T::Output) -> &str { "baz" }
```

In the two examples above, elision wasn't using lifetimes that were in the source, not even *needed* by paths in the source, but rather *happened* to be part of the semantic representation of the types.
To me, this suggests they should have never worked through elision (and they don't with this PR).

Next we have an actual rule with a strange result, that is, the return type here elides to `&'x str`:
```rust
impl<'a, 'b> Trait for Foo<'a, 'b> {
    fn method<'x, 'y>(self: &'x Foo<'a, 'b>, _: Bar<'y>) -> &str {
        &self.name
    }
}
```
All 3 of `'a`, `'b` and `'y` are being ignored, because the `&self` elision rule only cares that the first argument is "`self` by reference". Due implementation considerations (elision running before typeck), I've limited it in this PR to a reference to a primitive/`struct`/`enum`/`union`, but not other types, but I am doing another crater run to assess the impact of limiting it to literally `&self` and `self: &Self` (they're identical in HIR).

It's probably ideal to keep an "implicit `Self` for `self`" type around and *only* apply the rule to `&self` itself, but that would result in more bikeshed, and #21400 suggests some people expect otherwise.
Another decent option is treating `self: X, ... -> Y` like `X -> Y` (one unique lifetime in `X` used for `Y`).

The remaining changes have to do with "object lifetime defaults" (see RFCs [599](https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md) and [1156](https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md)):
```rust
trait Trait {}
struct Ref2<'a, 'b, T: 'a+'b>(&'a T, &'b T);

// These apply specifically within a (fn) body,
// which allows type and lifetime inference:
fn main() {
    // Used to be &'a mut (Trait+'a) - where 'a is one
    // inference variable - &'a mut (Trait+'b) in this PR.
    let _: &mut Trait;

    // Used to be an ambiguity error, but in this PR it's
    // Ref2<'a, 'b, Trait+'c> (3 inference variables).
    let _: Ref2<Trait>;
}
```
What's happening here is that inference variables are created on the fly by typeck whenever a lifetime has no resolution attached to it - while it would be possible to alter the implementation to reuse inference variables based on decisions made early by `resolve_lifetime`, not doing that is more flexible and works better - it can compile all testcases from #38624 by not ending up with `&'static mut (Trait+'static)`.

The ambiguity specifically cannot be an early error, because this is only the "default" (typeck can still pick something better based on the definition of `Trait` and whether it has any lifetime bounds), and having an error at all doesn't help anyone, as we can perfectly infer an appropriate lifetime inside the `fn` body.

**TODO**: write tests for the user-visible changes.

cc @nikomatsakis @arielb1

Rollup of 21 pull requests

- Successful merges: #38617, #39284, #39285, #39290, #39302, #39305, #39306, #39307, #39311, #39313, #39314, #39321, #39325, #39332, #39335, #39344, #39345, #39346, #39348, #39350, #39351
- Failed merges:

move `cast_kinds` into `TypeckTables` where it belongs

r? @EddyB

Use __SIZEOF_INT128__ to test __int128 presence

Previously we tested whether a handful of preprocessor variables indicating certain 64 bit
platforms, but this does not work for other 64 bit targets which have support for __int128 in C
compiler.

Use the `__SIZEOF__INT128__` preprocessor variable instead. This variable gets set to 16 by gcc and
clang for every target where __int128 is supported.

Fix cyryl's mailmap entry

Fix @jethrogb's mailmap entry

cc rust-lang-nursery/thanks#51

Fix up @carols10cents' mailmap entry

The previous ways didn't work; this does.

cc rust-lang-nursery/thanks#45

Fix a few links in the docs

r? @steveklabnik

Fix can_begin_expr keyword behavior

Partial fix for #28784.

Fix another endianness issue in i128 trans

Apparently LLVMArbitraryPrecisionInteger demands integers to be in low-endian 64-bytes, rather than host-endian 64-bytes. This is weird, and obviously, not documented. And rustc now works a teeny bit more on big endians.

r? @EddyB

doc comment typo fix

Rewrite the first sentence in slice::sort

For every method, the first sentence should consisely explain what it does,
not how. This sentence usually starts with a verb.

It's really weird for `sort` to be explained in terms of another function,
namely `sort_by`. There's no need for that because it's obvious how `sort`
sorts elements: there is `T: Ord`.

If `sort_by_key` does not have to explicitly state how it's implemented,
then `sort` doesn't either.

r? @steveklabnik

drop_in_place is stable now, don't #![feature] it in the nomicon and a test.

It was stable since Rust 1.8.

r? @GuillaumeGomez

Avoid ICE when pretty-printing non-local MIR item.

This comes up when using `-Zunstable-options --unpretty=mir`. Previously, rustc would ICE due to an unwrap later in this function (after `as_local_node_id`). Instead, we should just ignore items from other crates when pretty-printing MIR.

This was reported in #rust: [this playground code](https://is.gd/PSMBZS) causes an ICE if you click the MIR button. The problem is the mention of the non-local item `std::usize::MAX`, so you can reduce the test case [a lot](https://is.gd/SaLjaa).

r? @EddyB

std: Stabilize APIs for the 1.16.0 release

This commit applies the stabilization/deprecations of the 1.16.0 release, as
tracked by the rust-lang/rust issue tracker and the final-comment-period tag.

The following APIs were stabilized:

* `VecDeque::truncate`
* `VecDeque::resize`
* `String::insert_str`
* `Duration::checked_{add,sub,div,mul}`
* `str::replacen`
* `SocketAddr::is_ipv{4,6}`
* `IpAddr::is_ipv{4,6}`
* `str::repeat`
* `Vec::dedup_by`
* `Vec::dedup_by_key`
* `Result::unwrap_or_default`
* `<*const T>::wrapping_offset`
* `<*mut T>::wrapping_offset`
* `CommandExt::creation_flags` (on Windows)
* `File::set_permissions`
* `String::split_off`

The following APIs were deprecated

* `EnumSet` - replaced with other ecosystem abstractions, long since unstable

Closes #27788
Closes #35553
Closes #35774
Closes #36436
Closes #36949
Closes #37079
Closes #37087
Closes #37516
Closes #37827
Closes #37916
Closes #37966
Closes #38080

Add note for E0117

Fixes #39249.

I just applied the suggestion of @durka since I don't see anything else to add.

travis: Upload all artifacts in build/dist

Previously we only uploaded tarballs, but this modifies Travis/AppVeyor to
upload everything. We shouldn't have anything else in there to worry about and
otherwise we need to be sure to pick up pkg/msi/exe installers.

Hide uninhabitedness checks behind feature gate

This reverts the fix to match exhaustiveness checking so that it can be discussed. The new code is now hidden behind the `never_type` feature gate.

save-analysis: get tables directly, accomodating them being missing

Fixes an ICE when running with save-analysis after an error

r? @EddyB

rustbuild: Add manifest generation in-tree

This commit adds a new tool, `build-manifest`, which is used to generate a
distribution manifest of all produced artifacts. This tool is intended to
replace the `build-rust-manifest.py` script that's currently located on the
buildmaster. The intention is that we'll have a builder which periodically:

* Downloads all artifacts for a commit
* Runs `./x.py dist hash-and-sign`. This will generate `sha256` and `asc` files
  as well as TOML manifests.
* Upload all generated hashes and manifests to the directory the artifacts came
  from.
* Upload *all* artifacts (tarballs and hashes and manifests) to an archived
  location.
* If necessary, upload all artifacts to the main location.

This script is intended to just be the second step here where orchestrating
uploads and such will all happen externally from the build system itself.

cc #38531

Detect double reference when applying binary op

``` rust
let vr = v.iter().filter(|x| {
    x % 2 == 0
});
```

will now yield the following compiler output:

``` bash
ERROR binary operation `%` cannot be applied to type `&&_`
NOTE this is a reference of a reference to a type that `%` can be applied to,
you need to dereference this variable once for this operation to work
NOTE an implementation of `std::ops::Rem` might be missing for `&&_`
```

The first NOTE is new.

Fix #33877

----

Thanks to @estebank for providing the original PR #34420 (of which this is a tweaked rebase).