Clean up the zlib-related native code.

All the dude wanted was to get rid of Get/Release*Critical... First, though I
needed to switch the C files over to C++, and getting them to compile with a
stricter compiler made me realize how much of this stuff is unnecessary junk.
Eventually, I managed to get rid of all the "hy" and "sieb" crap, and you can
actually see what's going on now.

As usual, this reduces duplication and fixes leaks. I've also fixed a bug where
we'd never update inCap, meaning that we'd always allocate a new buffer and
never reuse the existing one even if it was large enough.

Bug: 2663177
Change-Id: I71fcbf9ff958ebf71ef3063d50ea34c28c30dd26
26 files changed