It's not the real deflateBound() in newer zlib libraries, partly because
the upcoming usage of it won't have the "stream" available, so we can't
have the same interfaces anyway.
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!