[m-rev.] for review: start using the new code in file_names.m

[Peter Wang]

On Sun, 11 Jun 2023 07:40:49 +1000 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> 
> +%           % XXX EXT Why aren't object files for grades that differ in e.g.
> +%           % whether debugging is enabled stored in grade-specific directories
> +%           % if --use-grade-subdirs is enabled? The .c files that they are
> +%           % derived from *are* stored in grade-specific directories.
> +%           % I (zs) expect that the reason why this hasn't been a problem
> +%           % is that we don't target C with --use-grade-subdirs.

I don't understand this comment. --use-grade-subdirs did always work
for C grades (with mmc --make), and object files were stored in
grade-specific directories.

Peter