update netinet/tcp.h for linux v4.2

TCP_CC_INFO is a new socket option to get congestion control info without
netlink (union tcp_cc_info is in linux/inet_diag.h kernel header).
linux commit 6e9250f59ef9efb932c84850cd221f22c2a03c4a

TCP_SAVE_SYN, TCP_SAVED_SYN socket options are for saving and getting the
SYN headers of passive connections in a server application.
linux commit cd8ae85299d54155702a56811b2e035e63064d3d

Add new tcpi_* fields to struct tcp_info implementing RFC4898 counters.
linux commit 2efd055c53c06b7e89c167c98069bab9afce7e59

include/netinet/tcp.h

@@ -27,6 +27,9 @@
 #define TCP_FASTOPEN     23
 #define TCP_TIMESTAMP    24
 #define TCP_NOTSENT_LOWAT 25
+#define TCP_CC_INFO      26
+#define TCP_SAVE_SYN     27
+#define TCP_SAVED_SYN    28
 
 #define TCP_ESTABLISHED  1
 #define TCP_SYN_SENT     2
@@ -177,6 +180,10 @@ struct tcp_info
 	uint32_t tcpi_total_retrans;
 	uint64_t tcpi_pacing_rate;
 	uint64_t tcpi_max_pacing_rate;
+	uint64_t tcpi_bytes_acked;
+	uint64_t tcpi_bytes_received;
+	uint32_t tcpi_segs_out;
+	uint32_t tcpi_segs_in;
 };
 
 #define TCP_MD5SIG_MAXKEYLEN    80