Commit 8572367b6814 ("pf: remove STATE_LOOKUP") introduced two seemingly
unintentional changes with respect to divert(4)-injected packets (i.e.,
the PACKET_LOOPED case): we no longer return the matching state, and
direct callers of pf_find_state() now treat matches of diverted packets
the same as having no matching state at all.
This seems inadvertent, and breaks certain rulesets which use divert-to.
Fix them, and add a regression test case.
Fixes: 8572367b6814 ("pf: remove STATE_LOOKUP")