TUN-813: Clean up cloudflared dependencies

vendor/golang.org/x/net/icmp/sys_freebsd.go

@@ -1,11 +0,0 @@
-// Copyright 2014 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.
-
-package icmp
-
-import "syscall"
-
-func init() {
-	freebsdVersion, _ = syscall.SysctlUint32("kern.osreldate")
-}