title: Error when installing mpi4py
body: <p>I'm trying to install mpi4py using pip install mpi4py, but I'm getting the following error: </p>
  
  <pre><code>error: Cannot find 'mpi.h' header. Check your configuration!!!
  </code></pre>
  
  <p>Earlier in the same error report I have,</p>
  
  <pre><code>clang: error: linker command failed with exit code 1 (use -v to see    invocation)
  </code></pre>
  
  <p>What might the problem be? </p>
  
  <p>Thanks!</p>