add AF_MPLS (PF_MPLS) address family to socket.h

new in linux 4.0 commit 0189197f441602acdca3f97750d392a895b778fd.

include/sys/socket.h

@@ -96,6 +96,7 @@ struct linger
 #define PF_WANPIPE      25
 #define PF_LLC          26
 #define PF_IB           27
+#define PF_MPLS         28
 #define PF_CAN          29
 #define PF_TIPC         30
 #define PF_BLUETOOTH    31
@@ -141,6 +142,7 @@ struct linger
 #define AF_WANPIPE      PF_WANPIPE
 #define AF_LLC          PF_LLC
 #define AF_IB           PF_IB
+#define AF_MPLS         PF_MPLS
 #define AF_CAN          PF_CAN
 #define AF_TIPC         PF_TIPC
 #define AF_BLUETOOTH    PF_BLUETOOTH