Update to kernel headers v4.12.3.

Test: Built angler.
Change-Id: Icbcf4fac2334de8409b049ed7a3b4c24b4e98ce9
diff --git a/libc/kernel/uapi/linux/ethtool.h b/libc/kernel/uapi/linux/ethtool.h
index 2bd4e6c..56df94b 100644
--- a/libc/kernel/uapi/linux/ethtool.h
+++ b/libc/kernel/uapi/linux/ethtool.h
@@ -619,6 +619,7 @@
 #define SPEED_2500 2500
 #define SPEED_5000 5000
 #define SPEED_10000 10000
+#define SPEED_14000 14000
 #define SPEED_20000 20000
 #define SPEED_25000 25000
 #define SPEED_40000 40000