[m-rev.] diff: avoid running some tests in decldebug grades

[Zoltan Somogyi]

On Tue, 9 Feb 2016 18:26:17 +1100 (AEDT), Julien Fischer <jfischer at opturion.com> wrote:
> tests/valid/Mmake.valid.common:
> tests/valid/Mmakefile:
> tests/valid_seq/Mmakefile:
>       Don't run valid/bug50 and valid/bug50_full in decldebug grades,
>       since they force the use of --trace deep.

After this diff, we now run those tests in hlc.gc grades, where they
obviously fail.

Zoltan.