enumoid regression: not structurally normalizing type in hir typeck pattern checking

https://crater-reports.s3.amazonaws.com/pr-133502-11/try%2328f13ad7c79d80decb5a3d54595a8b4105f397a3/reg/enumoid-0.4.0/log.txt

minimal:

```rust
trait Foo {
    type Bar;
}

impl Foo for () {
    type Bar = i32;
}

fn main() {
    const X: <() as Foo>::Bar = 0;

    match 0 {
        X..=X => {}
        _ => {}
    }
}
```