Before switching to distutils, we were statically linking the
VC runtime.

distutils, on the other hand, is enforcing dynamic linking. The
reason is that some extensions were hitting some runtime
limitations when statically linking it:
https://bugs.python.org/issue38597

This admittedly hacky patch will override the hardcoded distutils
/MD flag. It should work with all the supported Python versions.
For future versions, we're probably going to request the Python
community a better way of statically linking the runtime when
aware of the limitations.