Several changes to help with adding 64bit support.

* Change osx to osx32
* Change win to win32
* Change defaults from ['osx', 'win'] to ['osx32', 'osx64', 'win32', 'win64']
* Tried to hit some checks I missed.
* Change osx.json to osx32.json and win.json to win32.json
* Got failing tests down to 5....

I'm not really familiar with node unit testing, so I'm unsure how to
handle the rest of these failures.
@danthewolfe can you apply the same fix as https://github.com/adam-lynch/platform-overrides/commit/d41555cbc22684f9cefb6ae36c61364f4ef8641a#diff-66d14bf3d12add1ab55262539d9889e0R14 here? Just for Windows