Co-authored-by: Michael Goulet <michael@errs.io>

These files were added to the repository but never wired up so they could
be used - and that was a few years ago without anyone noticing - so let's
remove these, they can be re-added if someone wants them.

Signed-off-by: David Wood <david@davidtw.co>

Adds char to CFI integer normalization to conform to rust-lang#118032 for
cross-language CFI support.

discard invalid spans in external blocks

Fixes rust-lang#116203

This PR has discarded the invalid `const_span`, thereby making the format more neat.

r? ``@Nilstrieb``

Only check principal trait ref for object safety

It should make things a bit faster, in case we end up registering a bunch of object safety preds.

r? ```@ghost```

…r-errors

Add method to get type of an Rvalue in StableMIR

Provide a method to StableMIR users to retrieve the type of an Rvalue operation. There were two possible implementation:

1. Create the logic inside stable_mir to process the type according to the Rvalue semantics, which duplicates the logic of `rustc_middle::mir::Rvalue::ty()`.
2. Implement the Rvalue translation from StableMIR back to internal representation, invoke the `rustc_middle::mir::Rvalue::ty()`, and translate the return value to StableMIR.

I chose the first one for now since the duplication was fairly small, and the option 2 would require way more work to translate everything back to rustc internal representation. If we eventually add those translations, we could easily swap to the option 2.

```@compiler-errors``` / ```@ouz-a``` Please let me know if you have any strong opinion here.

r? ```@compiler-errors```

Ping GuillaumeGomez for changes in rustc_codegen_gcc

Since I work on it and also added its testsuite into rustc's CI, I'd like to know if there are changes.

…, r=compiler-errors

targets: remove not-added {i386,i486}-unknown-linux-gnu

These files were added to the repository but never wired up so they could be used - and that was a few years ago without anyone noticing - so let's remove these, they can be re-added if someone wants them.

cc rust-lang#80662
r? ```@pnkfelix``` (familiar with the tier policy and Wesley is on vacation)

…s-118032, r=compiler-errors

CFI: Add char to CFI integer normalization

Adds char to CFI integer normalization to conform to rust-lang#118032 for cross-language CFI support.