[m-rev.] for review: Update compare-by-RTTI code for changes introduced with subtypes.

[Julien Fischer]

On Wed, 7 Apr 2021, Peter Wang wrote:

> runtime/mercury_ho_call.c:
>    Include mercury_deconstruct_macros.h for macros used in the
>    following.
>
> runtime/mercury_unify_compare_body.h:
>    Use MR_index_or_search_ptag_layout to search du type layouts by
>    primary tag and MR_index_or_search_sectag_functor to search
>    sectag_alternatives by secondary tag, as required for subtypes.

That's fine.

Julien.