[Python-Dev] upgrading to zlib 1.2.1 for Windows

[Jeremy Hylton]

I noticed that a new version of zlib was released last year.  1.2.0 came
out in March through 1.2.1 in late November.  There are a lot of API
changes and new DLL support, but the new code seems to work fine with a
Python build.  That is, it compiles with minor changes to the build and
the tests all pass.  Even if we don't change our code at all, inflate is
about 20% faster and crc32 is about 50% faster.

Shall we upgrade the Windows build to use this new version?  I have the
changes made locally, but don't want to commit until people have had a
chance to grab the new source.

Jeremy