`use` can't resolve non-pub parent module through `super`

This use statement doesn't resolve:

```
mod foo {
    pub fn bar() { }
}

mod baz {
    use super::foo;
    fn main() {
        foo::bar();
    }
}
```

This one does:

```
mod foo {
    pub fn bar() { }
}

mod baz {
    use super::foo::bar;
    fn main() {
        bar();
    }
}
```
