build: fix build

Missing file during last CL.

TBR=r
CC=golang-dev
https://golang.org/cl/5505047

src/buildinfo.sh

+# Copyright 2011 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.
+
+# This file is included by shell scripts that need to know the
+# full list of architectures, operating systems, and combinations
+# that Go runs on.
+
+GOARCHES="
+	386
+	amd64
+	arm
+"
+
+GOOSES="
+	darwin
+	freebsd
+	linux
+	netbsd
+	openbsd
+	plan9
+	windows
+"
+
+GOOSARCHES="
+	darwin_386
+	darwin_amd64
+	freebsd_386
+	freebsd_amd64
+	linux_386
+	linux_amd64
+	linux_arm
+	netbsd_386
+	netbsd_amd64
+	openbsd_386
+	openbsd_amd64
+	plan9_386
+	windows_386
+	windows_amd64
+"