MFC 315529

MFC 315529

pf: Fix rule evaluation after inet6 route-to

In pf_route6() we re-run the ruleset with PF_FWD if the packet goes out
of a different interface. pf_test6() needs to know that the packet was
forwarded (in case it needs to refragment so it knows whether to call
ip6_output() or ip6_forward()).

This lead pf_test6() to try to evaluate rules against the PF_FWD
direction, which isn't supported, so it needs to treat PF_FWD as PF_OUT.
Once fwdir is set correctly the correct output/forward function will be
called.

PR:             217883
Submitted by:   Kajetan Staszkiewicz
Sponsored by:   InnoGames GmbH

git-svn-id: svn://svn.freebsd.org/base/stable/10@316000 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f