Rollup of 9 pull requests

Successful merges:

 - #50864 (Add NetBSD/arm target specs)
 - #50956 (rust-gdb: work around the re-used -d argument in cgdb)
 - #50964 (Make sure that queries have predictable symbol names.)
 - #50965 (Update LLVM to pull in another wasm fix)
 - #50972 (Add -Z no-parallel-llvm flag)
 - #50979 (Fix span for type-only arguments)
 - #50981 (Shrink `LiveNode`.)
 - #50995 (move type out of unsafe block)
 - #51011 ( rustdoc: hide macro export statements from docs)

Failed merges:

 rustdoc: hide macro export statements from docs

As mentioned in https://github.com/rust-lang/rust/issues/50647, rustdoc now prints both the import statement and the macro itself when re-exporting macros. This is a stopgap solution to clean up the std docs and get something small backported into beta.

What this does: When rustdoc finds an export statement for a macro, instead of printing the export and bailing, now it will instead hide the export and bail. Until we can solve https://github.com/rust-lang/rust/issues/34843 or have a better way to find the attributes on an export statement when inlining macros, this will at least match the current behavior and clean up the re-export statements from the docs.

move type out of unsafe block

from https://github.com/rust-lang/rust/pull/50863#discussion_r190213000

move the union definition outside of the unsafe block as it's definition is not unsafe

rustc_codegen_llvm: remove some debuginfo cruft.

(The second commit passes tests locally but might not on older LLVM versions)

r? @nikomatsakis

Shrink `LiveNode`.

`Liveness::users` is a vector that is occasionally enormous. For
example, doing a "clean incremental" check build of `inflate`, there is
one instance that represents 5,499 live nodes and 1087 vars, which
requires 5,977,413 entries. At 24 bytes per entry, that is 143MB.

This patch changes LiveNode from a usize to a u32. On 64-bit machines
that halves the size of these entries, significantly reducing peak
memory usage and memory traffic, and speeding up "clean incremental"
builds of `inflate` by about 10%.

Fix span for type-only arguments

Currently it points to the comma or parenthesis before the type, which is broken

cc @mark-i-m this is what broke #48309

r? @estebank

Add -Z no-parallel-llvm flag

Codegen issues commonly only manifest under specific circumstances,
e.g. if multiple codegen units are used and ThinLTO is enabled.
However, these configuration are threaded, making the use of LLVM
debugging facilities hard, as output is interleaved.

This patch adds a -Z no-parallel-llvm flag, which allows disabling
parallelization of codegen and linking, while otherwise preserving
behavior with regard to codegen units and LTO.

Update LLVM to pull in another wasm fix

Closes #50869

Make sure that queries have predictable symbol names.

Some recent refactorings led to query names not showing up in the corresponding symbol names. [perf-focus](https://github.com/nikomatsakis/perf-focus) and manual profiling have been broken by this. This PR makes sure that query providers always get their own symbol and that that symbol has a predictable name.

Since this adds `#[inline(never)]` to a function that wraps the provider call, let's check if this does not regress performance before merging.

r? @nikomatsakis

rust-gdb: work around the re-used -d argument in cgdb

Use --directory= to pass $GDB_PYTHON_MODULE_DIRECTORY instead of -d, because [cgdb](https://github.com/cgdb/cgdb) reuses '-d' to select a debugger, whereas the long option works with both gdb and cgdb.

Add NetBSD/arm target specs

rustc: Correctly pretty-print macro delimiters

This commit updates the `Mac_` AST structure to keep track of the delimiters
that it originally had for its invocation. This allows us to faithfully
pretty-print macro invocations not using parentheses (e.g. `vec![...]`). This in
turn helps procedural macros due to #43081.

Closes #50840

impl Trait diagnostic/test cleanups

"crate-ify" paths that begin with a renamed crate

This does two things:

- crate-ify paths that begin with a renamed crate (i.e., add `crate::`) to the front

Fixes https://github.com/rust-lang/rust/issues/50996

I also added tests for a few other scenarios.

r? @alexcrichton

Remove the unstable Float trait

Following up to #49896 and #50629. Fixes #32110.

Allow `Size` to be any valid `u64`

cc https://github.com/solson/miri/pull/378#issuecomment-390470725

The alternative is to make mir::interpret's pointer offsets not be `Size`

fixes #50917

r? @EddyB

Issue 50970 migration lint fq path

Similar issue, but for fully qualified paths.

Fixes #50970

r? @alexcrichton

Remove extra calls to kill_loans_out_of_scope_at_location.

r? @nikomatsakis

from https://github.com/rust-lang/rust/pull/50863#discussion_r190213000

move the union definition outside of the unsafe block

Use different datastructure for MIRI relocations

This PR makes relocations in MIRI used a sorted vector instead of a `BTreeMap` which should make a few common operations more efficient. Let's see if that's true.

r? @oli-obk

fixes #50970

Remove attribute_cache from CrateMetadata

This PR will fix #50508 by removing the `attribute_cache` from the `CrateMetadata` struct. Seeing as performance was referenced in the original issue, I also cleaned up a `self.entry(node_id);` call which might have occasionally happened redundantly.

r? @michaelwoerister

Generate "invalidates" facts when -Znll-facts is passed

Most of the new code is copied directly from the heart of the MIR borrowchecker. I was expecting more fundamental structural changes, hence the copying. This appears to work as it stands, but I'd like to submit a follow-up PR to reduce code duplication. I figured that could wait though, since this is blocking a large amount of work in the borrow check repository and I'm out of time for tonight =).

r? @nikomatsakis

Add lint for multiple associated types

Fix https://github.com/rust-lang/rust/issues/50589. cc @abonander

rustc: Fix another double-lint issue with `crate::`

This commit fixes another issue in the `absolute_path_not_starting_with_crate`
lint where it warns twice about an import which may contain `self`. It turns out
there were a few more locations that needed updating to use `root_id` and
`root_span` introduced in #50970 and after that it looks to work like a charm!

Closes #50978

This commit fixes another issue in the `absolute_path_not_starting_with_crate`
lint where it warns twice about an import which may contain `self`. It turns out
there were a few more locations that needed updating to use `root_id` and
`root_span` introduced in #50970 and after that it looks to work like a charm!

Closes #50978

`Liveness::users` is a vector that is occasionally enormous. For
example, doing a "clean incremental" check build of `inflate`, there is
one instance that represents 5,499 live nodes and 1087 vars, which
requires 5,977,413 entries. At 24 bytes per entry, that is 143MB.

This patch changes LiveNode from a usize to a u32. On 64-bit machines
that halves the size of these entries, significantly reducing peak
memory usage and memory traffic, and speeding up "clean incremental"
builds of `inflate` by about 10%.

Update rustfix

- Update compiletest to use rustfix 0.3.1

r? @Manishearth