title: Bazel macro fails with `name 'glob' is not defined`
body: <p>I defined a Bazel macro. It looks something like this:</p>
  
  <pre class="lang-py prettyprint-override"><code>def my_macro():
      java_binary(
          srcs = glob(["*.java"])
          # ...
      )
  </code></pre>
  
  <p>When I run Bazel, it fails with an error</p>
  
  <pre><code>ERROR: /home/.../macros.bzl:105:19: name 'glob' is not defined
  </code></pre>
  
  <p>Is it possible to use <code>glob</code> in a macro?</p>