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 rust-lang#65501.

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

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.

Fixes rust-lang#66787

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.

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.

parse_enum_item -> parse_enum_variant

r? @estebank

miri: add throw_machine_stop macro

r? @oli-obk
This helps Miri: rust-lang/miri#1093

…xcrichton

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

…obk,RalfJung

[const-prop] Fix ICE calculating enum discriminant

Fixes rust-lang#66787

Different approach than rust-lang#66857

r? @oli-obk
cc @RalfJung @eddyb

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 rust-lang#65501.

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

…Gomez

Add long error for E0631 and update ui tests.

This PR adds a long error for `E0631`, which covers errors where closure argument types are mismatched. It also updates UI tests where this error is applicable.

Part of rust-lang#61137