scratch/xiam: add main.go file.

Change-Id: If63481354adf6f47fb4fb17ef171afc566ac8d1a
Reviewed-on: https://go-review.googlesource.com/48723
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>

xiam/main.go

@@ -0,0 +1,11 @@
+// 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.
+
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello world!")
+}