tcp: add pacing_rate information into tcp_info

Add two new fields to struct tcp_info, to report sk_pacing_rate
and sk_max_pacing_rate to monitoring applications, as ss from iproute2.

User exported fields are 64bit, even if kernel is currently using 32bit
fields.

lpaa5:~# ss -i
..
	 skmem:(r0,rb357120,t0,tb2097152,f1584,w1980880,o0,bl0) ts sack cubic
wscale:6,6 rto:400 rtt:0.875/0.75 mss:1448 cwnd:1 ssthresh:12 send
13.2Mbps pacing_rate 3336.2Mbps unacked:15 retrans:1/5448 lost:15
rcv_space:29200

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 377f1e5..3b97183 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -186,6 +186,9 @@
 	__u32	tcpi_rcv_space;
 
 	__u32	tcpi_total_retrans;
+
+	__u64	tcpi_pacing_rate;
+	__u64	tcpi_max_pacing_rate;
 };
 
 /* for TCP_MD5SIG socket option */