windows/svc: add new package to help create and manage Windows services

Change-Id: I58bb446aaa387b31d8a9ff4217793a170b96a7e2
Reviewed-on: https://go-review.googlesource.com/9104
Reviewed-by: Rob Pike <r@golang.org>

windows/svc/go12.c

@@ -0,0 +1,24 @@
+// 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
+// +build !go1.3
+
+// copied from pkg/runtime
+typedef	unsigned int	uint32;
+typedef	unsigned long long int	uint64;
+#ifdef _64BIT
+typedef	uint64		uintptr;
+#else
+typedef	uint32		uintptr;
+#endif
+
+// from sys_386.s or sys_amd64.s
+void ·servicemain(void);
+
+void
+·getServiceMain(uintptr *r)
+{
+	*r = (uintptr)·servicemain;
+}