This is a continuation of #6314. Thanks to @welshjf for getting this rolling.
It's not as big/complicated as it looks at first glance, there are a few changes that add to the size:
- Split sources are now used rather than the huge complete tarball. 225M -> 75M. Thanks again to @welshjf for that.
- config options are now mostly one-per-line to make diffs easier to read
It's pretty straightforward otherwise.
Worth mentioning: I had to add 2 hacks for building with mingw. We need to make sure that all works well on win 8.1 and win10, as it looks like that's the path taken for the new (patched) code.