Since it's just a type alias this isn't too difficult and once Session
is moved back we can make this be the canonical location.

This commit breaks early-lint registration, which will be fixed in the
next commit. This movement will allow essentially all crates in the compiler
tree to declare lints (though not lint passes).

Rollup of 6 pull requests

Successful merges:

 - #66148 (Show the sign for signed ops on `exact_div`)
 - #66651 (Add `enclosing scope` parameter to `rustc_on_unimplemented`)
 - #66904 (Adding docs for keyword match, move)
 - #66935 (syntax: Unify macro and attribute arguments in AST)
 - #66941 (Remove `ord` lang item)
 - #66967 (Remove hack for top-level or-patterns in match checking)

Failed merges:

r? @ghost

Remove hack for top-level or-patterns in match checking

Follow-up to #66612.

Or-patterns are now truly first-class in match checking. As a side-effect, redundant subpatterns are linted as such, making the `unreachable_patterns` lint a bit more general.

cc #54883

r? @varkor

Remove `ord` lang item

At this point it seems to be unused, and just `partial_ord` is used instead. This removes the unused lang item.

syntax: Unify macro and attribute arguments in AST

The unified form (`ast::MacArgs`) represents parsed arguments instead of an unstructured token stream that was previously used for attributes.
It also tracks some spans and delimiter kinds better for fn-like macros and macro definitions.

I've been talking about implementing this with @nnethercote in https://github.com/rust-lang/rust/pull/65750#issuecomment-546517322.
The parsed representation is closer to `MetaItem` and requires less token juggling during conversions, so it potentially may be faster.

r? @Centril

Adding docs for keyword match, move

Partial fix of issue #34601.

Add `enclosing scope` parameter to `rustc_on_unimplemented`

Adds a new parameter to `#[rustc_on_unimplemented]`, `enclosing scope`, which highlights the function or closure scope with a message.

The wip part refers to adding this annotation to `Try` trait to improve ergonomics (which I don't know how to do since I change both std and librustc)

Closes #61709.

Show the sign for signed ops on `exact_div`

r? @RalfJung Cc https://github.com/rust-lang/miri/pull/961/files#r341842128

I'm fairly unhappy with the duplication and the general effort required for this.

Maybe it would be better to add a `display` impl for `ImmTy`?

submodules: update clippy from 7b8e8293 to 45196cee

Changes:
````
account for external macro in MISSING_INLINE_IN_PUBLIC_ITEMS lint
build(tests/fmt): use shared target dir
chore: fix and split some ui tests on 32bit system
build: set up build job for i686 targets
remove needless my_lint ui test
git quiet
deploy: cd to out/ before adding files to git
Less needless_doctest_main false positives
fmt
Feed the dog
Use rustc_env instead of exec_env for test
Make triggering this lint less likely 📎
Use exec_env to set backtrace level and normalize output
Update custom ICE function with latest rustc
Use Clippy version in ICE message
Add custom ICE message that points to Clippy repo
Fix master deployment
Run update_lints
Add projections check to EUV for escape analysis
Use infer_ctxt
Move use_self to nursery
Use `println!` on success instead of `eprintln!`
Revert "Disable chalk integration test. Output too large"
Remove the old integration-tests.sh script
Use rust implementation for integration tests in CI
Rust implementation of integration test
Don't error on clippy.toml of dependencies
Fix categorizations
Fix arguments on ExprUseVisitor::new
euv moved from middle to typeck
cmt_ -> Place
build: check if RTIM is not installed
make use of Result::map_or
trigger string_lit_as_bytes when literal has escapes
Remove negative float literal checks.
Enable deny-warnings feature everywhere in CI
Remove unused debugging feature
implemented `as_conversions` lint
fixing a typo
[comparison_chain] #4827 Check `core::cmp::Ord` is implemented
add a good example for the approx_const lint
Add suggested good cases in docs for lifetimes lint
````
Fixes #66840

Layout::pad_to_align is infallible

As per [this comment](https://github.com/rust-lang/rust/issues/55724#issuecomment-441421651) (cc @glandium).

> Per https://github.com/rust-lang/rust/blob/eb981a1/src/libcore/alloc.rs#L63-L65, `layout.size()` is always <= `usize::MAX - (layout.align() - 1)`.
>
> Which means:
>
> * The maximum value `layout.size()` can have is already aligned for `layout.align()` (`layout.align()` being a power of two, `usize::MAX - (layout.align() - 1)` is a multiple of `layout.align()`)
> * Incidentally, any value smaller than that maximum value will align at most to that maximum value.
>
> IOW, `pad_to_align` can not return `Err(LayoutErr)`, except for the layout not respecting its invariants, but we shouldn't care about that.

This PR makes `pad_to_align` return `Layout` directly, representing the fact that it cannot fail.

Changes:
````
Normalize custom ICE test
Rustup to rust-lang/rust#64736
Use assert_crate_local for a more explicit error
Rustup to https://github.com/rust-lang/rust/pull/66789
account for external macro in MISSING_INLINE_IN_PUBLIC_ITEMS lint
build(tests/fmt): use shared target dir
chore: fix and split some ui tests on 32bit system
build: set up build job for i686 targets
remove needless my_lint ui test
git quiet
deploy: cd to out/ before adding files to git
Less needless_doctest_main false positives
fmt
Feed the dog
Use rustc_env instead of exec_env for test
Make triggering this lint less likely 📎
Use exec_env to set backtrace level and normalize output
Update custom ICE function with latest rustc
Use Clippy version in ICE message
Add custom ICE message that points to Clippy repo
Fix master deployment
Run update_lints
Add projections check to EUV for escape analysis
Use infer_ctxt
Move use_self to nursery
Use `println!` on success instead of `eprintln!`
Revert "Disable chalk integration test. Output too large"
Remove the old integration-tests.sh script
Use rust implementation for integration tests in CI
Rust implementation of integration test
Don't error on clippy.toml of dependencies
Fix categorizations
Fix arguments on ExprUseVisitor::new
euv moved from middle to typeck
cmt_ -> Place
build: check if RTIM is not installed
make use of Result::map_or
trigger string_lit_as_bytes when literal has escapes
Remove negative float literal checks.
Enable deny-warnings feature everywhere in CI
Remove unused debugging feature
implemented `as_conversions` lint
fixing a typo
[comparison_chain] #4827 Check `core::cmp::Ord` is implemented
add a good example for the approx_const lint
Add suggested good cases in docs for lifetimes lint
````

Also remove a couple of redundant `visit_mac` asserts

We want the lifetimes of the patterns contained in the matrix and the
candidate `PatStack` to be the same so that they can be mixed together.
A lot of this would not be necessary if `SmallVec` was covariant in its
type argument (see https://github.com/servo/rust-smallvec/issues/146).