[m-rev.] for review: Skip debugging tests in parallel grades.

[Julien Fischer]

On Fri, 18 Nov 2022, Peter Wang wrote:

> Since commit f380d2c36, the compiler refuses to allow debugging in
> parallel grades.
>
> tests/debugger/Mmakefile:
> tests/declarative_debugger/Mmakefile:
>    Skip debugging tests in parallel grades.

That's fine.

Julien.