I vaguely recall seeing some discussion about this on python-dev or elsewhere and wish I had chimed in sooner, as I didn't realize action was going to be taken on this so soon.

This completely breaks building extension modules on Windows-based platforms like Cygwin and MinGW, where it is necessary when building even shared libraries for all global symbols to resolvable at link time.

I'm not actually sure this use case can even be achieved on these platforms.  I tried several hacks but nothing works.  I'll open a follow-up issue...