tests: use built-in require.progs instead of custom solution

[igoro]

Summary

If you don't mind I would recommend to use existing functionality of Kyua/ATF. In order to get it a bit cleaner and declarative with no code. And not to get it copy-pasted and distributed among the new tests -- I guess I could be the first victim here to copy-paste my own test w/o extra caution :).

[lwhsu]

Oh yes thanks for reminding, this is indeed the better solution.

[igoro]

Align the patch with the main.

[igoro]

Covered by https://reviews.freebsd.org/D47105.