wg: fix build without pf

[Klemens Nanni]

Feedback? OK?


Index: sys/net/if_wg.c
===================================================================
RCS file: /cvs/src/sys/net/if_wg.c,v
retrieving revision 1.9
diff -u -p -r1.9 if_wg.c
--- sys/net/if_wg.c     10 Jul 2020 13:26:42 -0000      1.9
+++ sys/net/if_wg.c     12 Jul 2020 16:31:03 -0000
@@ -1666,7 +1666,9 @@ wg_decap(struct wg_softc *sc, struct mbu
        m->m_pkthdr.ph_ifidx = sc->sc_if.if_index;
        m->m_pkthdr.ph_rtableid = sc->sc_if.if_rdomain;
        m->m_flags &= ~(M_MCAST | M_BCAST);
+#if NPF > 0
        pf_pkt_addr_changed(m);
+#endif /* NPF > 0 */
 
 done:
        t->t_mbuf = m;