pf tests: test wildcard anchors

Ensure that a wildcard anchor actually includes any nested anchors (i.e.
foo/* will call into foo/bar).

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D36414

(cherry picked from commit d5a0bf4517c053803b266742d16be456c5393ae7)