add TCP_NLA_* enums from linux v4.11

two new stats for SCM_TIMESTAMPING_OPT_STATS, added in linux commit
7e98102f489775d8c000884fca8a0d995ea688a9

include/netinet/tcp.h

@@ -50,6 +50,8 @@ enum {
 	TCP_NLA_BUSY,
 	TCP_NLA_RWND_LIMITED,
 	TCP_NLA_SNDBUF_LIMITED,
+	TCP_NLA_DATA_SEGS_OUT,
+	TCP_NLA_TOTAL_RETRANS,
 };
 
 #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)