add vendor

vendor/golang.org/x/text/language/go1_2.go

@@ -0,0 +1,12 @@
+// Copyright 2013 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.
+
+//go:build go1.2
+// +build go1.2
+
+package language
+
+import "sort"
+
+var sortStable = sort.Stable