Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/erspan.h b/libc/kernel/uapi/linux/erspan.h
new file mode 100644
index 0000000..790a85e
--- /dev/null
+++ b/libc/kernel/uapi/linux/erspan.h
@@ -0,0 +1,43 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef _UAPI_ERSPAN_H
+#define _UAPI_ERSPAN_H
+#include <linux/types.h>
+#include <asm/byteorder.h>
+struct erspan_md2 {
+  __be32 timestamp;
+  __be16 sgt;
+#ifdef __LITTLE_ENDIAN_BITFIELD
+  __u8 hwid_upper : 2, ft : 5, p : 1;
+  __u8 o : 1, gra : 2, dir : 1, hwid : 4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+  __u8 p : 1, ft : 5, hwid_upper : 2;
+  __u8 hwid : 4, dir : 1, gra : 2, o : 1;
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
+};
+struct erspan_metadata {
+  int version;
+  union {
+    __be32 index;
+    struct erspan_md2 md2;
+  } u;
+};
+#endif