[m-rev.] for review: Fix deep copying of subtype terms.

[Julien Fischer]

On Wed, 7 Apr 2021, Peter Wang wrote:

> runtime/mercury_deep_copy.c:
>    Include mercury_deconstruct_macros.h for
>    MR_index_or_search_ptag_layout and
>    MR_index_or_search_sectag_functor.
>
> runtime/mercury_deep_copy_body.h:
>    Use the macros to search a du type layout by primary tag or a
>    sectag_alternatives array by secondary tag, which is necessary
>    for subtypes.
>
> runtime/mercury_deconstruct.c:
> runtime/mercury_ml_expand_body.h:
> runtime/mercury_term_size.c:
> runtime/mercury_unify_compare_body.h:
>    Add comments where we can and can't directly index a du type layout
>    or sectag alternatives array.
>
> tests/hard_coded/subtype_rtti.m:
> tests/hard_coded/subtype_rtti.exp:
> tests/hard_coded/subtype_rtti.exp2:
>    Test deep copying of subtype terms.

That's fine.

Julien.