ddns+forward+tsig: not changing msgID in general packet wire

instead of hard-changing msgID in packet wire, which breaks msgID for the response, we just
set the original msgID when computing the tsig hash to check against

src/libknot/packet/pkt.c

@@ -700,7 +700,6 @@ static int check_rr_constraints(knot_pkt_t *pkt, knot_rrset_t *rr, size_t rr_siz
 			pkt->size -= rr_size;
 			pkt->tsig_wire.pos = pkt->wire + pkt->parsed;
 			pkt->tsig_wire.len = rr_size;
-			knot_wire_set_id(pkt->wire, knot_tsig_rdata_orig_id(rr));
 			knot_wire_set_arcount(pkt->wire, knot_wire_get_arcount(pkt->wire) - 1);
 		}
 		break;

src/libknot/tsig-op.c

@@ -546,6 +546,9 @@ static int check_digest(const knot_rrset_t *tsig_rr,
 	memset(wire_to_sign, 0, size);
 	memcpy(wire_to_sign, wire, size);
 
+	// restore message ID to which the signature had been created with
+	knot_wire_set_id(wire_to_sign, knot_tsig_rdata_orig_id(tsig_rr));
+
 	uint8_t digest_tmp[KNOT_TSIG_MAX_DIGEST_SIZE];
 	size_t digest_tmp_len = 0;
 	assert(tsig_rr->rrs.rr_count > 0);