add SO_ getsockopt options from linux v4.13
SCM_TIMESTAMPING_PKTINFO is new in aad9c8c470f2a8321a99eb053630ce0e199558d6
SO_PEERGROUPS is new in 28b5ba2aa0f55d80adb2624564ed2b170c19519e
diff --git a/include/sys/socket.h b/include/sys/socket.h
index bcaf87f..051d20e 100644
--- a/include/sys/socket.h
+++ b/include/sys/socket.h
@@ -228,6 +228,8 @@
#define SO_MEMINFO 55
#define SO_INCOMING_NAPI_ID 56
#define SO_COOKIE 57
+#define SCM_TIMESTAMPING_PKTINFO 58
+#define SO_PEERGROUPS 59
#ifndef SOL_SOCKET
#define SOL_SOCKET 1