Update to kernel headers v4.12.3.

Test: NA
Change-Id: Iee3d607e8a0fe866ffa1f123308af0713719ea29
diff --git a/original/uapi/linux/seg6_iptunnel.h b/original/uapi/linux/seg6_iptunnel.h
index 0f7dbd2..b6e5a0a 100644
--- a/original/uapi/linux/seg6_iptunnel.h
+++ b/original/uapi/linux/seg6_iptunnel.h
@@ -14,6 +14,8 @@
 #ifndef _UAPI_LINUX_SEG6_IPTUNNEL_H
 #define _UAPI_LINUX_SEG6_IPTUNNEL_H
 
+#include <linux/seg6.h>		/* For struct ipv6_sr_hdr. */
+
 enum {
 	SEG6_IPTUNNEL_UNSPEC,
 	SEG6_IPTUNNEL_SRH,
@@ -33,6 +35,8 @@
 	SEG6_IPTUN_MODE_ENCAP,
 };
 
+#ifdef __KERNEL__
+
 static inline size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
 {
 	int encap = (tuninfo->mode == SEG6_IPTUN_MODE_ENCAP);
@@ -42,3 +46,5 @@
 }
 
 #endif
+
+#endif