Disable ctypes extension when using "Visual Studio 2008 Win64" generator.
Disable ctypes extension when using "Visual Studio 2008 Win64" generator.

See http://public.kitware.com/Bug/view.php?id=8170 for more details.

thewtex/python-cmake-buildsystem,python-cmake-buildsystem/python-cmake-buildsystem,adrianbroher/python-cmake-buildsystem,thewtex/python-cmake-buildsystem,jcfr/python-cmake-buildsystem,davidsansome/python-cmake-buildsystem,chuckatkins/python-cmake-buildsystem,msmolens/python-cmake-buildsystem