Check if partial match doesn't exceed maximum offset boundary.

Change-Id: I477c849e562bf1390dba8b772e1cf25371d4bcd4

src/libknot/packet/response.c

@@ -55,7 +55,7 @@ static bool knot_response_compr_score(uint8_t *n, uint8_t *p, uint8_t labels,
 	}
 
 	/* New best score. */
-	if (score > match->lbcount) {
+	if (score > match->lbcount && off <= KNOT_WIRE_PTR_MAX) {
 		match->lbcount = score;
 		match->off = off;
 		return true;