32-bit rustc data corruption

After the latest snapshot rustc would mysteriously fail in stage1, building libsyntax:

```
rust: task failed at 'The .times method expects a nonnegative number, but found -43', /home/brian/dev/rust2/src/librustc/rustc.rc:1
```

To work around this I am adding a single debug statement to `rustc::middle::privacy`, with a FIXME containing this bug number.
