title: How to identify compiler before defining cython extensions?
body: <p>I'm building a platform independent cython project where I want to pass compiler args based on the compiler being used. I can guess the compiler based on platform or assume it's the same compiler used for Python but it's not guaranteed to match. Normally I inject into the <code>cmdclass</code> arg to setuptool's setup method and wrap the install or build_ext commands to check internal state. But in this case I have to cythonize the extension modules before I reach the wrappers.</p>
  
  <p>Is there any way to determine the compiler inside setup.py before cythonizing the extension modules?</p>