fixed one small typo

gtests/net/packetdrill/run_packet.c

@@ -636,7 +636,7 @@ static int map_inbound_sctp_packet(
 			nr_gap_blocks = ntohs(sack->nr_gap_blocks);
 			nr_dup_tsns = ntohs(sack->nr_dup_tsns);
 
-			if (ntohs(sack->length) == (sizeof(struct sctp_sack_chunk)+(sizeof(union sctp_sack_block()))*nr_gap_blocks+(sizeof(union sctp_sack_block))*nr_dup_tsns)) {
+			if (ntohs(sack->length) == (sizeof(struct sctp_sack_chunk)+(sizeof(union sctp_sack_block))*nr_gap_blocks+(sizeof(union sctp_sack_block))*nr_dup_tsns)) {
 				for (i = 0; i < nr_dup_tsns; i++) {
 					sack->block[i + nr_gap_blocks].tsn = htonl(ntohl(sack->block[i + nr_gap_blocks].tsn) + local_diff);
 				}