TUN-813: Clean up cloudflared dependencies

vendor/golang.org/x/sys/plan9/mksysnum_plan9.sh

@@ -1,23 +0,0 @@
-#!/bin/sh
-# Copyright 2009 The Go Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
-
-COMMAND="mksysnum_plan9.sh $@"
-
-cat <<EOF
-// $COMMAND
-// MACHINE GENERATED BY THE ABOVE COMMAND; DO NOT EDIT
-
-package plan9
-
-const(
-EOF
-
-SP='[ 	]' # space or tab
-sed "s/^#define${SP}\\([A-Z0-9_][A-Z0-9_]*\\)${SP}${SP}*\\([0-9][0-9]*\\)/SYS_\\1=\\2/g" \
-	< $1 | grep -v SYS__
-
-cat <<EOF
-)
-EOF