In most places, we use a span when emitting `expected...found` errors.
However, there were a couple of places where we didn't use any span,
resulting in hard-to-interpret error messages.

This commit attaches the relevant span to these notes, and additionally
switches over to using `note_expected_found` instead of manually
formatting the message

update Miri

Fixes https://github.com/rust-lang/rust/issues/66862

r? @ghost

Rollup of 7 pull requests

Successful merges:

 - #66750 (Update the `wasi` crate for `wasm32-wasi`)
 - #66878 (Move Sessions into (new) librustc_session)
 - #66903 (parse_enum_item -> parse_enum_variant)
 - #66951 (miri: add throw_machine_stop macro)
 - #66957 (Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld)
 - #66960 ([const-prop] Fix ICE calculating enum discriminant)
 - #66973 (Update the minimum external LLVM to 7)

Failed merges:

r? @ghost

Update the minimum external LLVM to 7

LLVM 7 is over a year old, which should be plenty for compatibility. The
last LLVM 6 holdout was llvm-emscripten, which went away in #65501.

I've also included a fix for LLVM 8 lacking `MemorySanitizerOptions`,
which was broken by #66522.

[const-prop] Fix ICE calculating enum discriminant

Fixes #66787

Different approach than #66857

r? @oli-obk
cc @RalfJung @EddyB

Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld

Changed linker for `x86_64-fortanix-unknown-sgx` target to `rust-lld`
This change needed the RelaxELFRelocations flag to be set for it to work correctly

r? @jethrogb

miri: add throw_machine_stop macro

r? @oli-obk
This helps Miri: https://github.com/rust-lang/miri/pull/1093

parse_enum_item -> parse_enum_variant

r? @estebank

Move Sessions into (new) librustc_session

This PR moves `ParseSess` and `Session` from their current locations into a new crate, `librustc_session`.

There are several intents behind this change. librustc is a very large crate, and we want to split it up over time -- this movement removes the sizeable session module from it. It also helps allow for future movement of things not coupled to TyCtxt but coupled to Session out of the crate.

This movement allows allows for a future follow-up PR which unifies Session and ParseSess, allowing for a single source of truth for APIs interested in global options throughout the compiler; the ParseSess is already created directly as a member of Session in the current compiler (i.e., we do not first construct a ParseSess and then move it into Session later in the compilation).

This PR intentionally avoids changing numerous imports throughout the tree to new locations of the moved types; this is needless noise and can be done as needed.

In the process of moving the sessions back, the lint system received an update as well -- notably, early buffered lints are no longer ad-hoc declared as enum pairs and later associated with proper lint declarations. They are still separately handled (buffered), it is a little unclear whether this is truly necessary, but regardless is left for future PRs.

Many of the types moved back are sort of ad-hoc placed into the same crate (librustc_session) instead of creating other crates; it's unclear whether this is actually a good thing, but it seemed better than creating numerous tiny crates which served no purpose on their own.

Update the `wasi` crate for `wasm32-wasi`

This commit updates the `wasi` crate used by the standard library which
is used to implement most of the functionality of libstd on the
`wasm32-wasi` target. This update comes with a brand new crate structure
in the `wasi` crate which caused quite a few changes for the wasi target
here, but it also comes with a significant change to where the
functionality is coming from.

The WASI specification is organized into "snapshots" and a new snapshot
happened recently, so the WASI APIs themselves have changed since the
previous revision. This had only minor impact on the public facing
surface area of libstd, only changing on `u32` to a `u64` in an unstable
API. The actual source for all of these types and such, however, is now
coming from the `wasi_preview_snapshot1` module instead of the
`wasi_unstable` module like before. This means that any implementors
generating binaries will need to ensure that their embedding environment
handles the `wasi_preview_snapshot1` module.

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).

This commit updates the `wasi` crate used by the standard library which
is used to implement most of the functionality of libstd on the
`wasm32-wasi` target. This update comes with a brand new crate structure
in the `wasi` crate which caused quite a few changes for the wasi target
here, but it also comes with a significant change to where the
functionality is coming from.

The WASI specification is organized into "snapshots" and a new snapshot
happened recently, so the WASI APIs themselves have changed since the
previous revision. This had only minor impact on the public facing
surface area of libstd, only changing on `u32` to a `u64` in an unstable
API. The actual source for all of these types and such, however, is now
coming from the `wasi_preview_snapshot1` module instead of the
`wasi_unstable` module like before. This means that any implementors
generating binaries will need to ensure that their embedding environment
handles the `wasi_preview_snapshot1` module.

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

Fixes #66787

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

For SGX, the relocation using the relocation table is done by
the code in rust/src/libstd/sys/sgx/abi/reloc.rs and this code
should not require relocation. Setting RelaxELFRelocations flag
if allows this to happen, hence adding a Target Option for it.