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/windows/eventlog.go

@@ -0,0 +1,20 @@
+// Copyright 2012 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
+
+package windows
+
+const (
+	EVENTLOG_SUCCESS          = 0
+	EVENTLOG_ERROR_TYPE       = 1
+	EVENTLOG_WARNING_TYPE     = 2
+	EVENTLOG_INFORMATION_TYPE = 4
+	EVENTLOG_AUDIT_SUCCESS    = 8
+	EVENTLOG_AUDIT_FAILURE    = 16
+)
+
+//sys	RegisterEventSource(uncServerName *uint16, sourceName *uint16) (handle Handle, err error) [failretval==0] = advapi32.RegisterEventSourceW
+//sys	DeregisterEventSource(handle Handle) (err error) = advapi32.DeregisterEventSource
+//sys	ReportEvent(log Handle, etype uint16, category uint16, eventId uint32, usrSId uintptr, numStrings uint16, dataSize uint32, strings **uint16, rawData *byte) (err error) = advapi32.ReportEventW