Fix test::run-pass::reflect-visit-data.rs

Two FIXMEs:

```
        // FIXME: Inner really has to move its own pointers on this one.
        // or else possibly we could have some weird interface wherein we
        // read-off a word from inner's pointers, but the read-word has to
        // always be the same in all sub-pointers? Dubious.
```

and

```
this needs to rewind between enum variants, or something.
```
