Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/linux/neighbour.h b/libc/kernel/uapi/linux/neighbour.h
index d239e72..1a322de 100644
--- a/libc/kernel/uapi/linux/neighbour.h
+++ b/libc/kernel/uapi/linux/neighbour.h
@@ -41,6 +41,7 @@
   NDA_IFINDEX,
   NDA_MASTER,
   NDA_LINK_NETNSID,
+  NDA_SRC_VNI,
   __NDA_MAX
 };
 #define NDA_MAX (__NDA_MAX - 1)