title: Force setup.py to use my custom compiler
body: <p>I'm trying to get setup.py to compile c++ code with the macports version of gcc. The problem is the code I am trying to build, doesn't support mac's default clang, which is the default gcc on newer osx versions.</p>
  
  <p>I created a custom <code>setup.cfg</code> file </p>
  
  <p>setup.cfg</p>
  
  <pre><code>[build_ext] 
  compiler=gcc-mp-4.8
  </code></pre>
  
  <p>However when I run <code>python setup.py build_ext</code> I get the following error</p>
  
  <p>running build_ext</p>
  
  <pre><code>error: don't know how to compile C/C++ code on platform 'posix' with 'gcc-mp-4.8' compiler
  </code></pre>
  
  <p>How can I get setup.py to use my version of gcc <code>gcc-mp-4.8</code>?</p>
  
  <p>Currently setup.py defaults to using <code>/usr/bin/clang</code>,  when i type <code>gcc -v</code> it shows that it is using gcc version 4.8.2</p>