[m-rev.] for review: reenable selective clearing StatusMap

[Peter Wang]

On Tue, 12 Dec 2023 07:34:39 +1100 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> Restore selected clearing of the status map.
> 
> compiler/make.program_target.m:
>     Remove an old workaround, which has not been needed since 2009.

That's fine.

Testing mmc --make libfoo.install reveals that we were forgetting to
clear the mki_target_file_timestamps cache before installing a library
grade, which somehow *seemed* to work anyway, until commit 0529340e4.
I'll post a fix for that soon.

Peter