[m-rev.] for review: write direct to .err files

[Zoltan Somogyi]

On 2023-09-15 15:06 +10:00 AEST, "Julien Fischer" <jfischer at opturion.com> wrote:
> I cannot think of an instance when such call pair nesting could occur.
> Peter, can you?

The circumstances I was thinking of were, roughly, where

- making A.c  requires A.int
- making A.c requires B.mh which requires A.opt.

I don't know enough about mmc --make to rule out
either scenario.
 
> In any case, I think the change is fine as you will still end up with
> the severity_error errors in the .err file (and they're the ones a user
> needs to address.)

That is pretty much my thinking.

BTW, this diff fixes the failure of one test case in the csharp grade.
Before this diff, the warnings/warn_self_import test case failed
because the .err file contained *three* copies of the warning being
tested for, instead of the expected one copy.

Zoltan.