[m-rev.] for review: extend the use of library grade install checks

[Zoltan Somogyi]

On Sat, 14 Sep 2019 02:12:53 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
> Perform library grade install checks when the compiler is invoked on a single
> source file linked target; previously we only performed this checks when using
> mmc --make.

I presume the intention is to provide context for any linker error messages
that arise from missing installed grades?
 
> +maybe_check_libraries_are_installed(Globals, Succeeded, !IO) :-
> +    globals.lookup_bool_option(Globals, libgrade_install_check,
> +        LibgradeCheck),
> +    (
> +        LibgradeCheck = yes,
> +        globals.lookup_accumulating_option(Globals, mercury_libraries, Libs),
> +        grade_directory_component(Globals, Grade),

I would s/Grade/GradeDirName/ here. While the directory names
are the same as the grades themselves for now, conceptually, they
are different things.

The diff is otherwise fine.

Zoltan.