vendor: explicitly vendor golang.org/x/sys

Vendor golang.org/x/sys to get the UtimesNanoAt function defined for all
unix-like OSes. The function will be used in a successive commit.

This also re-vendors the other dependencies from glide.yaml.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

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

@@ -0,0 +1,24 @@
+// Copyright 2017 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.
+
+// Functions to access/create device major and minor numbers matching the
+// encoding used in Darwin's sys/types.h header.
+
+package unix
+
+// Major returns the major component of a Darwin device number.
+func Major(dev uint64) uint32 {
+	return uint32((dev >> 24) & 0xff)
+}
+
+// Minor returns the minor component of a Darwin device number.
+func Minor(dev uint64) uint32 {
+	return uint32(dev & 0xffffff)
+}
+
+// Mkdev returns a Darwin device number generated from the given major and minor
+// components.
+func Mkdev(major, minor uint32) uint64 {
+	return (uint64(major) << 24) | uint64(minor)
+}