Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

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

@@ -0,0 +1,29 @@
+// 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 OpenBSD's sys/types.h header.
+
+package unix
+
+// Major returns the major component of an OpenBSD device number.
+func Major(dev uint64) uint32 {
+	return uint32((dev & 0x0000ff00) >> 8)
+}
+
+// Minor returns the minor component of an OpenBSD device number.
+func Minor(dev uint64) uint32 {
+	minor := uint32((dev & 0x000000ff) >> 0)
+	minor |= uint32((dev & 0xffff0000) >> 8)
+	return minor
+}
+
+// Mkdev returns an OpenBSD device number generated from the given major and minor
+// components.
+func Mkdev(major, minor uint32) uint64 {
+	dev := (uint64(major) << 8) & 0x0000ff00
+	dev |= (uint64(minor) << 8) & 0xffff0000
+	dev |= (uint64(minor) << 0) & 0x000000ff
+	return dev
+}