internal_reference_types

[Richard Kenner]

> Only Richard K. might remember the details.  Possibly for
> IA-64/HP-UX -milp32.  In any case, having a different representation
> for pointers and references is a recipe for annoying issues like
> this, so removing the kludge is OK with me.

I don't think I added that.  In fact, I'm not sure what the term
"address spaces' address_mode" means: I think that was added after I
stopped working on GCC.  So I don't know either.  Is it ever called?