Import the _random module

This worries me :/  It's definitely a step in the right direction, but moving from "always crashing" to "sometimes works" puts us in an uncomfortable place where bugs could happen and we wouldn't know about it.  For instance, tp_new isn't getting set when __new__ gets set, and __new__ isn't getting updated when tp_new gets changed.

Maybe a short-term solution is that we could clear tp_new at the end of this block?  Or maybe set it to a function that crashes with something more helpful than a random segfault :P  It's not very nice, but at least that way we'd know that no one was trying to use tp_new before we support it for real.