title: Installing guppy with pip3 issues
body: <p>I am trying to install <a href="https://pypi.python.org/pypi/guppy/" rel="noreferrer">guppy</a>. My program uses python3 so I must use pip3 exclusively. When I run:</p>
  
  <pre><code>pip3 install guppy
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>src/sets/sets.c:77:1: error: expected function body after function declarator
  INITFUNC (void)
  ^
  src/sets/sets.c:39:18: note: expanded from macro 'INITFUNC'
  #define INITFUNC initsetsc
                   ^
  1 error generated.
  error: command 'clang' failed with exit status 1
  </code></pre>
  
  <p>I tried doing <a href="https://stackoverflow.com/questions/10238458/cant-install-orange-error-command-clang-failed-with-exit-status-1">this</a>, even thourgh it wasn't the same and exported gcc and g++:</p>
  
  <pre><code>➜  ~ export CC=gcc
  ➜  ~ export CXX=g++
  </code></pre>
  
  <p>Running again:</p>
  
  <pre><code>src/sets/sets.c:77:1: error: expected function body after function declarator
  INITFUNC (void)
  ^
  src/sets/sets.c:39:18: note: expanded from macro 'INITFUNC'
  #define INITFUNC initsetsc
                   ^
  1 error generated.
  error: command 'gcc' failed with exit status 1
  </code></pre>
  
  <p>Most who had this issue used <code>sudo apt-get python-dev</code> or something of the like to resolve this issue, I couldn't find an equivalent for Mac. Is there a way to resolve this issue?</p>