For references to addresses of constant strings, we make an entry in
reloc.CODE and configure the relocation type to say it points at a
memory address. (At least I think this is right, I can't test it yet!)
The same info can also be used for de-duplication.
It turns out we don't need reloc.DATA. I had misunderstood it.
The use case for that would be constant nested data structures,
where constant data would contain pointers to other constant data.
I don't think we're doing this in Roc at all, but not sure.