portlist: don't depend on tempfork/osexec on iOS, saves 90KB

This gives us 90KB more of memory on iOS, as it shrinks the
NetworkExtension binary by 90KB.

The netstat binary isn't available in the network extension anyway, so
no point pulling in the osexec package which'll just fail to find
netstat anyway.

portlist/portlist_ios.go

@@ -0,0 +1,22 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin,!amd64
+
+package portlist
+
+import (
+	"errors"
+	"time"
+)
+
+const pollInterval = 9999 * time.Hour
+
+func listPorts() (List, error) {
+	return nil, errors.New("not implemented")
+}
+
+func addProcesses(pl []Port) ([]Port, error) {
+	return nil, errors.New("not implemented")
+}

portlist/portlist_macos.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !linux,!windows
+// +build darwin,amd64
 
 package portlist