Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/linux/netconf.h b/libc/kernel/uapi/linux/netconf.h
index 981badd..4f86757 100644
--- a/libc/kernel/uapi/linux/netconf.h
+++ b/libc/kernel/uapi/linux/netconf.h
@@ -31,6 +31,7 @@
   NETCONFA_MC_FORWARDING,
   NETCONFA_PROXY_NEIGH,
   NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
+  NETCONFA_INPUT,
   __NETCONFA_MAX
 };
 #define NETCONFA_MAX (__NETCONFA_MAX - 1)