title: Find all the uses of a metadata node
body: <p>I have an <code>MDNode*</code> (found using <code>DebugInfoFinder</code>). I want to find out all the other <code>MDNode</code>s in the module that use it, but its use list appears to be empty. How do I find that?</p>
  
  <p>For example, I have something like:</p>
  
  <pre><code>...
  !5 = metadata !{i32 100}
  ...
  !8 = metadata !{i32 101, metadata !5}
  ...
  </code></pre>
  
  <p>If I have <code>metadata !{i32 100}</code>, how do I get a reference to <code>metadata !{i32 101, metadata !5}</code>?</p>