Enum (and enum define) auto-generated marshallers do not persist across modules

If I use use #enum hooks like this:

```
{#enum my_enum as MyEnum {underscoreToCase} #}

{#fun unsafe my_func as ^ { `MyEnum' } -> `()' #}
```

This works as expected. If, though, I move #fun hook into separate module and use #import, then I get an error about unknown default marshaller. I suspect that this needs a change in interface files format.
