SCons: avoid checks leftovers

[vassilit]

Closes: #685

echo "" | cc -xc - -c generates a '-.o' leftover (gcc/clang).

[fermino]

Thanks for the fix, I will merge it as soon as it passes CI.

[fermino]

@vassilit would you mind changing https://github.com/sahib/rmlint/blob/master/.github/workflows/build-and-test.yml#L12 to ubuntu-22.04? ubuntu-latest is now 24.04 and there has python imp's module seems to have been removed.

This change should eventually be caught by #677, but for now it'd be nice to have this merged.
If you add it in a different commit I will fast-forward master so the changes are not mixed.

Thanks again! :)

Related issue: actions/runner-images#10636

Edit: wrong link.