[m-rev.] for post-commit review: take foreign_import_modules out of item type

[Julien Fischer]

On Thu, 22 Aug 2019, Zoltan Somogyi wrote:

> For review by anyone.
>
> Take foreign_import_modules out of the item type.
> 
> compiler/prog_item.m:
>     Even though we express foreign import module declarations syntactically
>     as pragmas, semantically, they are much closer to import_module
>     declarations. This means that the treatment they require in most places
>     in the compiler is similar to the treatment of import_module declarations,
>     and quite different from the treatment of other kinds of items.
>     Therefore this diff takes foreign_import_module declarations (FIMs
>     for short) out of item type. From now on, in parse trees and their
>     components, FIMs are stored in data structures of their own, next to
>     import_module declarations.
> 
> compiler/parse_types.m:
>     Provide a mechanism for the parser to return FIMs as an entity kind
>     of its own, not as an item.
> 
> compiler/comp_unit_interface.m:
>     Conform to the changes above, and give a predicate a more specific name.
> 
> compiler/module_qual.m:
>     Conform to the changes above, and require .int3 files to contain no FIMs.

That's fine.

Julien.