zlib 1.3.2. (zlib-1.3.2.tar.gz)
Files not required by OpenMPT have been removed.
OpenMPT specific changes:
 *  `zconf.h` has been modified to avoid preprocessor warnings.
 *  `gzread.c` and `gzwrite.c` have been modified to work on platforms without
    EWOULDBLOCK..
 *  `contrib/minizip/iowin32.c` has been modified to only use Windows 8 WinRT
    API when actually compiling for Windows 8 or later.
 *  `contrib/minizip/zip.c` has been modified to check for allocation failure. A
    similar fix has been proposed upstream:
    <https://github.com/madler/zlib/pull/566>
 *  All custom modifications are marked with /* OpenMPT */
 *  For building, premake is used to generate Visual Studio project files.
    See ../build/premake/ for details.
No further changes have been made.
