rustc_driver: expose a way to override query providers in CompileController.

This API has been a long-time coming and will probably become the main method for custom drivers (that is, binaries other than `rustc` itself that use `librustc_driver`) to adapt the compiler's behavior.

Fix MIR borrowck EndRegion not found

Fixes #45702

- [x] Add Tests

Handle closures correctly in MIR inlining

Fixes #45894.

always add an unreachable branch on matches to give more info to llvm

As part of https://github.com/djzin/rustc-optimization I discovered that some simple enum optimizations (src/unary/three_valued_enum.rs and src/unary/four_valued_enum.rs in the repo) are not applied - and the reason for this is that we erase the info that the discriminant of an enum is one of the options by putting the last one in an "otherwise" branch. This patch adds an extra branch so that LLVM can know what the possibilities are for the discriminant, which fixes the three- and four- valued cases.

Note that for whatever reason, this doesn't fix the case of 2 variants (most notably `Option` and `Result` have 2 variants) - a pass re-ordering might fix this or we may wish to add "assume" annotations on discriminants to force it to optimize.

Rollup of 7 pull requests

- Successful merges: #45815, #45941, #45950, #45961, #45967, #45970, #45977
- Failed merges:

Fixed several pulldown warnings when documenting libstd.

Add missing links in FromStr docs

r? @QuietMisdreavus

MIR-borrowck: don't ICE for cannot move from array error

Closes #45694
compile-fail test E0508 now gives
```text
error[E0508]: cannot move out of type `[NonCopy; 1]`, a non-copy array (Ast)
  --> .\src\test\compile-fail\E0508.rs:18:18
   |
18 |     let _value = array[0];  //[ast]~ ERROR E0508
   |                  ^^^^^^^^
   |                  |
   |                  cannot move out of here
   |                  help: consider using a reference instead: `&array[0]`

error[E0508]: cannot move out of type `[NonCopy; 1]`, a non-copy array (Mir)
  --> .\src\test\compile-fail\E0508.rs:18:18
   |
18 |     let _value = array[0];  //[ast]~ ERROR E0508
   |                  ^^^^^^^^ cannot move out of here

error: aborting due to 2 previous errors
```

Use #!/usr/bin/env as shebang for Bash scripts

On some systems, the bash command could be available in another
directory than /bin. As such, to offer an env shebang is more
convenient.

This make sense even for docker scripts, as you can use Docker
on FreeBSD or SmartOS for example.

Rollup merge of #45950 - fitzgen:update-unary-and-binary-exprs-test-to-use-incr-except, r=michaelwoerister

incr: Make `unary_and_binary_exprs.rs` use `except`-style incremental checking

Part of #44924

r? @michaelwoerister

update match-expressions.rs with DepNode labels

As a part of #44924, I have updated the match-expressions.rs. The PR has tests verified for the following dependency nodes for let-expressions

- MirValidated
- MirOptimized
- TypeCheckTables
- TypeOfItem
- GenericsOfItem
- PredicatesOfItem
- FnSignature

cc @michaelwoerister
r? @nikomatsakis

rustdoc: tweak notes on ignore/compile_fail examples

Part of https://github.com/rust-lang/rust/issues/44927

This is a softening of these notices to mention *why* a given example has a given callout, rather then telling viewers to be careful with an example. It also changes the character used for these samples from a warning logo to a circle-i/information logo.

![image](https://user-images.githubusercontent.com/5217170/32464361-5fbb5d9e-c305-11e7-8482-ce71b97a54df.png)

Use getrandom syscall for all Linux and Android targets.

I suppose we can use it in all Linux and Android targets. In function `is_getrandom_available` is checked if the syscall is available (getrandom syscall was add in version 3.17 of Linux kernel), if the syscall is not available `fill_bytes` fallback to reading from `/dev/urandom`.

Update libc to include getrandom related constants.

rustc_mir: hardcode pass list internally and remove premature pluggability.

Fixes #41712 by moving the MIR pass lists from `rustc_driver` to `rustc_mir`.
The application of the passes is done with the `rustc_mir::transform::run_passes` macro, which is public, as are all the passes AFAIK, and can be used to apply MIR passes outside of `rustc_mir`.

With the ability to override query providers through the `rustc_driver` (orthogonal to, and not included in this PR), custom drivers will be able to substitute the entire pass list if they want to.
**EDIT**: the aforementioned ability is added by #45944.

r? @nikomatsakis

always add an unreachable branch on matches to give more info to llvm about which values are possible

incr.comp.: Don't crash in DepGraph::try_mark_green() when encountering a removed input node.

Fixes a small regression that was introduced in #45867.

r? @nikomatsakis

Normalize inlined function in MIR inliner

Fixes #45885

r? @arielb1

MIR-borrowck: add permisson checks to `fn access_lvalue`

WIP : Some FIXME left and some broken tests.

Fix #44837

Distribute Rustfmt

r? @alexcrichton

check::method - unify receivers before normalizing method signatures

Normalizing method signatures can unify inference variables, which can
cause receiver unification to fail. Unify the receivers first to avoid
that.

Fixes #36701.
Fixes #45801.
Fixes #45855.

r? @EddyB

beta-nominating because #43880 made this ICE happen in more cases (the code in that issue ICEs post-#43880 only, but the unit test here ICEs on all versions).