Could it be possible to to make the debug build absolutely abort on any usage of PyType's that are not readied, usage including instantiating them. Then, instead of changing all `static` linkages to `extern`s (as in Serhiy's first patch) one could rather make per-compilation unit initialization functions that are called from objects.c; that way it would be easier to use preprocessor to turn on and off the very existence of certain types in a compilation unit based on a preprocessor flag.

Likewise the C-API docs for PyType_Ready should perhaps say "This must be called on all type objects to finish their initialization." instead of "should"