lib/model: Handle filename conflicts on Windows.

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3810
LGTM: calmh

lib/osutil/name_conflict.go

@@ -0,0 +1,17 @@
+// Copyright (C) 2016 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/.
+
+// +build !windows
+
+package osutil
+
+// CheckNameConflict returns true if every path component of name up to and
+// including filepath.Join(base, name) doesn't conflict with any existing
+// files or folders with different names. Base and name must both be clean and
+// name must be relative to base.
+func CheckNameConflict(base, name string) bool {
+	return true
+}