save-analysis doesn't dump ref entry for struct name in static method calls

Here's a small testcase:

```rust
struct Foo {
}

impl Foo {
  fn new() {
  }
}

fn main() {
  Foo::new();
}
```

If you run this through `rustc -Z save-analysis` and look at the save-analysis JSON file, you'll see that there is no entry for the `Foo` part of `Foo::new()`. This seems like a bug.