Rename TyLayout to TyAndLayout.

add test for 62220

Closes rust-lang#62220

Adds a test for rust-lang#62220.

Im not sure whether `check-pass` is sufficient here. I didn't put `run-pass` in, as I'm afraid that'll fail due to the `unimplemented!()` return in the code.

… r=varkor

#[link]: mention wasm_import_module instead of cfg

`#[link(cfg)]` is perma-unstable and is not documented anywhere else. It makes more sense to mention `wasm_import_module` here since it's stable.

This makes it harder to hit rust-lang#70538 (if it weren't for this text, I wouldn't even know this feature existed).

prohibit_generics: update has_err for consts

r? @eddyb