Make it possible to build v2.9 on Windows with recent MinGW32 releases

We build binary eggs for Python 2.4 and 2.5 using MinGW32. Due to http://bugs.python.org/issue12641 we have to use gcc 4.5. It doesn't appear to be possible to reproduce that build environment anymore, so we have to work around the distutils bug.

Note that this fix will only be applied to PyMongo 2.x. PyMongo 3.x does not support Python 2.4 and 2.5. C extensions for later versions of Python can be built with the Microsoft Visual C++ compiler for Python 2.7 (which also works for Python 2.6), or more modern versions of Visual Studio. See this list for recommendations:

https://wiki.python.org/moin/WindowsCompilers