I've run into this quite a few times when working with characterization test
infra. It would print an invalid command:
_NIX_TEST_ACCEPT=1 meson test main/lang
Which you'd then proceed to run and it would fail. This commit makes it
be honest about the command you need to run:
_NIX_TEST_ACCEPT=1 meson test --suite main lang
It seems that `meson test --print-errorlogs` only captures stderr,
so this makes it forward the logs as intended.
We might want to redirect stdout in our common setup script instead.
