update upload.go to use Google Cloud Storage

[bradfitz]

upload.go uses the Google Code file hosting, which no longer exists.

we now host winstrap.exe at https://storage.googleapis.com/winstrap/winstrap-20140711.exe

but that was done by hand. update upload.go to use GCS uploads instead. See for an example of how to do this at:

https://code.google.com/p/go/source/browse/dashboard/coordinator/buildongce/create.go?repo=tools

func writeCloudStorageObject(httpClient *http.Client) {
        content := os.Stdin
        const maxSlurp = 1 << 20
        var buf bytes.Buffer
        n, err := io.CopyN(&buf, content, maxSlurp)
        if err != nil && err != io.EOF {
                log.Fatalf("Error reading from stdin: %v, %v", n, err)
        }
        contentType := http.DetectContentType(buf.Bytes())

        req, err := http.NewRequest("PUT", "https://storage.googleapis.com/"+*writeObject, io.MultiReader(&buf, content))
        if err != nil {
                log.Fatal(err)
        }
        req.Header.Set("x-goog-api-version", "2")
        req.Header.Set("x-goog-acl", "public-read")
        req.Header.Set("Content-Type", contentType)
        res, err := httpClient.Do(req)
        if err != nil {
                log.Fatal(err)
        }
        if res.StatusCode != 200 {
                res.Write(os.Stderr)
                log.Fatalf("Failed.")
        }
        log.Printf("Success.")
        os.Exit(0)
}

It just needs an oauth2 http.Client & token first.