unix: add socket error queue constants and types from linux/errqueue.h

Also add additional packet timestamping constants and types defined
in the same header.

Change-Id: I4280f925b46e229f4c3a83a7fee4612592314016
Reviewed-on: https://go-review.googlesource.com/c/158761
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/linux/types.go

@@ -47,6 +47,7 @@ package unix
 #include <sys/user.h>
 #include <sys/utsname.h>
 #include <sys/wait.h>
+#include <linux/errqueue.h>
 #include <linux/filter.h>
 #include <linux/icmpv6.h>
 #include <linux/if_pppox.h>
@@ -1643,7 +1644,9 @@ const (
 	NCSI_CHANNEL_ATTR_VLAN_ID       = C.NCSI_CHANNEL_ATTR_VLAN_ID
 )
 
-// SO_TIMESTAMPING flags
+// Timestamping
+
+type ScmTimestamping C.struct_scm_timestamping
 
 const (
 	SOF_TIMESTAMPING_TX_HARDWARE  = C.SOF_TIMESTAMPING_TX_HARDWARE
@@ -1664,4 +1667,12 @@ const (
 
 	SOF_TIMESTAMPING_LAST = C.SOF_TIMESTAMPING_LAST
 	SOF_TIMESTAMPING_MASK = C.SOF_TIMESTAMPING_MASK
+
+	SCM_TSTAMP_SND   = C.SCM_TSTAMP_SND
+	SCM_TSTAMP_SCHED = C.SCM_TSTAMP_SCHED
+	SCM_TSTAMP_ACK   = C.SCM_TSTAMP_ACK
 )
+
+// Socket error queue
+
+type SockExtendedErr C.struct_sock_extended_err