Remove windows specialisation from osutil.GetLans (fixes #2192)

lib/osutil/lan.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2015 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package osutil
+
+import (
+	"net"
+)
+
+func GetLans() ([]*net.IPNet, error) {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return nil, err
+	}
+
+	nets := make([]*net.IPNet, 0, len(addrs))
+
+	for _, addr := range addrs {
+		net, ok := addr.(*net.IPNet)
+		if ok {
+			nets = append(nets, net)
+		}
+	}
+	return nets, nil
+}