"newtype" structs fail to work across crates

a.rs:

``` rust
pub struct Foo { x : int }
pub struct Bar( int );
```

b.rs:

``` rust
extern mod a;
use a::*;

fn main() {
    let foo = Foo { x : 0 };
    let bar = Bar( 0 );
}
```

_rustc --lib a.rs && rustc -L. b.rs_ yields:

```
b.rs:6:11: 6:14 error: unresolved name: Bar
b.rs:6  let bar = Bar( 0 );
                  ^~~
```
