Remove cruft from our zlib-1.2.6 import.

There was a ton of cruft lying around from earlier versions. I want to move us
to be as close to upstream as possible, so upgrades are simpler and quicker,
and I can be more confident of what I'm doing. This is a first step.

Change-Id: I526a64969ff2a5bf25067fae4530560acf095225
41 files changed