The attached patch adds platform tags for .pyd files for "win32", "win-arm", "win-amd64" and "win-ia64", which are the known compilers in pyconfig.h and the potential return values from distutils.util.get_platform(). It also fixes a bug where the suffix would be incorrect if building a debug extension.

I haven't been able to think of any scenarios where this could break other than perhaps packaging (since distutils defaults to including the tag), and we've got plenty of time to sort those issues out. A quick test installing Cython and some packages built with Cython seemed to be fine. AIUI, MinGW/cygwin builds won't use PC/pyconfig.h, and so they won't see any change.