Yay for (some) Perl support!

The Perl validation seems to be restricted to "compile with warnings", despite "perlcritic" being now almost 15 years old, predating both some other linters' and even some other languages' very existence.

I'll try to see how feasible it'd be to add it as a ("the"?) Perl linter to be used as using just the compilation step to infer everything's fine doesn't really satisfy the role a linter is meant to have.