[starnix][iptables] Restore xt_mark.h

This header is needed to implement the MARK target for starnix.

Change-Id: I83934c6ad1fe863b63e12026a93893be9ca3c3f7
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/android.googlesource.com/platform/bionic/+/1238444
Reviewed-by: Sergey Ulanov <sergeyu@google.com>
diff --git a/libc/kernel/uapi/linux/netfilter/xt_mark.h b/libc/kernel/uapi/linux/netfilter/xt_mark.h
new file mode 100644
index 0000000..f828919
--- /dev/null
+++ b/libc/kernel/uapi/linux/netfilter/xt_mark.h
@@ -0,0 +1,17 @@
+/*
+ * This file is auto-generated. Modifications will be lost.
+ *
+ * See https://android.googlesource.com/platform/bionic/+/master/libc/kernel/
+ * for more information.
+ */
+#ifndef _XT_MARK_H
+#define _XT_MARK_H
+#include <linux/types.h>
+struct xt_mark_tginfo2 {
+  __u32 mark, mask;
+};
+struct xt_mark_mtinfo1 {
+  __u32 mark, mask;
+  __u8 invert;
+};
+#endif