pf: Copy kif flags to userspace

This was overlooked in the pfi_kkif/pfi_kif splitup and as a result
userspace could no longer tell which interfaces had the skip flag
applied.

MFC after:	2 weeks

sys/netpfil/pf/pf_if.c

@@ -829,6 +829,7 @@ pf_kkif_to_kif(const struct pfi_kkif *kkif, struct pfi_kif *kif)
 			}
 		}
 	}
+	kif->pfik_flags = kkif->pfik_flags;
 	kif->pfik_tzero = kkif->pfik_tzero;
 	kif->pfik_rulerefs = kkif->pfik_rulerefs;
 }