This is the venerable zlib:
http://zlib.net/

A subset of version 1.2.3 is included here.  There are a few small changes.

Source:
http://zlib.net/fossils/zlib-1.2.3.tar.gz

SHA 256 checksum:
1795c7d067a43174113fdf03447532f373e1c6c57c08d61d9e4e9be5e244b05e

Changes:
 - CMakeLists.txt added
 - more...