Run (make vendor)

Temporarily vendor opencontainers/image-spec from a fork
to fix "id" value duplication, which is detected and
refused by gojsonschema now
( https://github.com/opencontainers/image-spec/pull/750 ).

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/golang.org/x/sys/windows/aliases.go

@@ -0,0 +1,13 @@
+// Copyright 2018 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 windows
+// +build go1.9
+
+package windows
+
+import "syscall"
+
+type Errno = syscall.Errno
+type SysProcAttr = syscall.SysProcAttr