Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/if_tun.h b/libc/kernel/uapi/linux/if_tun.h
index d8757a1..6a3c75e 100644
--- a/libc/kernel/uapi/linux/if_tun.h
+++ b/libc/kernel/uapi/linux/if_tun.h
@@ -49,6 +49,8 @@
 #define TUNGETVNETLE _IOR('T', 221, int)
 #define TUNSETVNETBE _IOW('T', 222, int)
 #define TUNGETVNETBE _IOR('T', 223, int)
+#define TUNSETSTEERINGEBPF _IOR('T', 224, int)
+#define TUNSETFILTEREBPF _IOR('T', 225, int)
 #define IFF_TUN 0x0001
 #define IFF_TAP 0x0002
 #define IFF_NAPI 0x0010