cmd/go: add missing files (fix build)

TBR=r
CC=golang-dev
https://golang.org/cl/5571050

src/cmd/go/bootstrap.go

+// 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 cmd_go_bootstrap
+
+// This code is compiled only into the bootstrap 'go' binary.
+// These stubs avoid importing packages with large dependency
+// trees, like the use of "net/http" in vcs.go.
+
+package main
+
+import "errors"
+
+func httpGET(url string) ([]byte, error) {
+	return nil, errors.New("no http in bootstrap go command")
+}

src/cmd/go/http.go

+// 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 !cmd_go_bootstrap
+
+// This code is compiled into the real 'go' binary, but it is not
+// compiled into the binary that is built during all.bash, so as
+// to avoid needing to build net (and thus use cgo) during the
+// bootstrap process.
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+// httpGET returns the data from an HTTP GET request for the given URL.
+func httpGET(url string) ([]byte, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("%s: %s", url, resp.Status)
+	}
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("%s: %v", url, err)
+	}
+	return b, nil
+}