pf tests: IPv6 test case for the 'kill state(s)' feature
Reviewed by: donner
MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D29797
(cherry picked from commit 9af2317423f399b30ff028e078d01eef553efc7f)