Add more TCP_* values to netinet/tcp.h.

This patch adds move TCP_* values to sysdeps/gnu/netinet/tcp.h to
bring it up to date with Linux 4.2.  TCP_SAVE_SYN and TCP_SAVED_SYN
are new in 4.2, TCP_NOTSENT_LOWAT and TCP_CC_INFO are older (Szabolcs
previously noted in
<https://sourceware.org/ml/libc-alpha/2015-06/msg00938.html> that this
header was out of date in glibc).

Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by the patch).

	* sysdeps/gnu/netinet/tcp.h (TCP_NOTSENT_LOWAT): New macro.
	(TCP_CC_INFO): Likewise.
	(TCP_SAVE_SYN): Likewise.
	(TCP_SAVED_SYN): Likewise.

ChangeLog

@@ -1,3 +1,10 @@
+2015-09-01  Joseph Myers  <joseph@codesourcery.com>
+
+	* sysdeps/gnu/netinet/tcp.h (TCP_NOTSENT_LOWAT): New macro.
+	(TCP_CC_INFO): Likewise.
+	(TCP_SAVE_SYN): Likewise.
+	(TCP_SAVED_SYN): Likewise.
+
 2015-08-31  Brett Neumeier <brett@neumeier.us>
 
 	[BZ #18870]

sysdeps/gnu/netinet/tcp.h

@@ -61,6 +61,14 @@
 #define TCP_REPAIR_OPTIONS	 22 /* Repair TCP connection options */
 #define TCP_FASTOPEN		 23 /* Enable FastOpen on listeners */
 #define TCP_TIMESTAMP		 24 /* TCP time stamp */
+#define TCP_NOTSENT_LOWAT	 25 /* Limit number of unsent bytes in
+				       write queue.  */
+#define TCP_CC_INFO		 26 /* Get Congestion Control
+				       (optional) info.  */
+#define TCP_SAVE_SYN		 27 /* Record SYN headers for new
+				       connections.  */
+#define TCP_SAVED_SYN		 28 /* Get SYN headers recorded for
+				       connection.  */
 
 #ifdef __USE_MISC
 # include <sys/types.h>