Ignore `core`, `alloc` and `test` tests that require unwinding on `-C panic=abort`
Some of the tests for `core` and `alloc` require unwinding through their use of `catch_unwind`. These tests fail when testing using `-C panic=abort` (in my case through a target without unwinding support, and `-Z panic-abort-tests`), while they should be ignored as they don't indicate a failure.
This PR marks all of these tests with this attribute:
```rust
#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
```
I'm not aware of a way to test this on rust-lang/rust's CI, as we don't test any target with `-C panic=abort`, but I tested this locally on a Ferrocene target and it does indeed make the test suite pass.
When building as part of rust, the sysroot source dir is symlinked to
the main source dir, which contains the build dir to which we are likely
copying.
Add MVP suggestion for `unsafe_op_in_unsafe_fn`
Rebase of https://github.com/rust-lang/rust/pull/99827
cc tracking issue https://github.com/rust-lang/rust/issues/71668
No real changes since the original PR, just migrated the new suggestion to use fluent messages and added a couple more testcases, AFAICT from the discussion there were no outstanding changes requested.
Adjust UI tests for `unit_bindings` lint
- Explicitly annotate `let x: () = expr;` where `x` has unit type, or remove the unit binding to leave only `expr;` instead.
- Use `let () = init;` or `let pat = ();` where appropriate.
- Fix disjoint-capture-in-same-closure test which wasn't actually testing a closure: `tests/ui/closures/2229_closure_analysis/run_pass/disjoint-capture-in-same-closure.rs`.
Note that unfortunately there's *a lot* of UI tests, there are a couple of places where I may have left something like `let (): ()` (this is not needed but is left over from an ealier version of the lint) which is bad style.
This PR is to help with the `unit_bindings` lint at #112380.
loongarch64-unknown-none*: Set default relocation model to static
This PR sets the default relocation model to `static` for `loongarch64-unknown-none*` targets. This change aims to streamline the development of the bare-metal project by removing the need for the executable program loader to implement relocation.
