Run additional test targets

[henridf]

Currently, passing -T leads to the test make target being run.

It would be handy if it were possible to run the other testing-related targets (check_license, style unused, and staticcheck).

Assuming there is no objection to this, I'm happy to put up a PR. I could:

• just keep a single -T flag, and expand the set of make targets that it runs to include the above
• add some separate testing flag(s) to cover those other targets

Any preferences?