title: How to change `sourceMappingURL` by using webpack
body: <p>My production webpack configuration is:</p>
  
  <pre><code>{
    output: {
      publicPath: "https://cdn.example.com/sub-directory/",
      filename: '[name]-[chunkhash].min.js'
    },
  
    devtool: 'source-map',
  
    plugins: [
      new webpack.optimize.UglifyJsPlugin()
    ]
  }
  </code></pre>
  
  <p>Now I have two files <code>app-12345.min.js</code> and <code>app-12345.min.js.map</code>.</p>
  
  <p>I also have automatically generated CDN URL <code>https://cdn.example.com/sub-directory/app-12345.min.js</code> for main script.</p>
  
  <p>But <code>sourceMappingURL</code> is still relative path <code>//# sourceMappingURL=app-12345.min.js.map</code> and not accessible directly in browser.</p>
  
  <p>My question is how I can set <code>sourceMappingURL</code> as absolute automatically generated path?</p>