add dep management

vendor/golang.org/x/sys/unix/endian_little.go

@@ -0,0 +1,9 @@
+// Copyright 2016 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.
+//
+// +build 386 amd64 amd64p32 arm arm64 ppc64le mipsle mips64le
+
+package unix
+
+const isBigEndian = false