Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/pkt_cls.h b/libc/kernel/uapi/linux/pkt_cls.h
index 4bac8f9..113469c 100644
--- a/libc/kernel/uapi/linux/pkt_cls.h
+++ b/libc/kernel/uapi/linux/pkt_cls.h
@@ -380,6 +380,7 @@
 #define TCA_FLOWER_MAX (__TCA_FLOWER_MAX - 1)
 enum {
   TCA_FLOWER_KEY_FLAGS_IS_FRAGMENT = (1 << 0),
+  TCA_FLOWER_KEY_FLAGS_FRAG_IS_FIRST = (1 << 1),
 };
 enum {
   TCA_MATCHALL_UNSPEC,
@@ -429,7 +430,8 @@
 #define TCF_EM_VLAN 6
 #define TCF_EM_CANID 7
 #define TCF_EM_IPSET 8
-#define TCF_EM_MAX 8
+#define TCF_EM_IPT 9
+#define TCF_EM_MAX 9
 enum {
   TCF_EM_PROG_TC
 };