[m-rev.] for review: implement the rest of the extension changes proposal

[Julien Fischer]

On Thu, 17 Aug 2023, Zoltan Somogyi wrote:

> Put all executable/library files into grade-specific directories ...
> 
> ... with --use-grade-subdirs.
> 
> compiler/file_names.m:
>     Move all the executable and library extensions to the ext_cur_gs group,
>     which means their files get put into grade-specific directories if
>     --use-grade-subdirs is set.
>
>     Comment out the enums representing the .lib and .so extensions,
>     because they are never specified specifically as those extensions;
>     they are only ever referred to though the options holding
>     those extensions.
>
>     Put all executable files into subdirs named "bin", and all libraries
>     into subdirs named "lib". Rename the subdirs for several other extensions
>     as well, as we agreed on m-rev.
> 
> compiler/make.program_target.m:
>     Conform to the change above.
>
>     Delete duplicate computation of the filename of an "mmc --make" target.
>
>     Use a direct test of filenames to see whether a file needs to be
>     linked-or-copied to the current directory.
>
>     If the action of generating an executable does not execute cleanly,
>     clean up not just the full pathname version of the file, but its
>     current directory copy as well (in case it was the copy that
>     got the error, due to e.g. the filesystem being full).
> 
> compiler/write_deps_file.m:
>     Conform to the change above.
>
>     Delete a repeated computation.
> 
> compiler/compile_target_code.m:
>     Conform to the change above.

That's fine.

Julien.