The project that builds libpng under Borland C++ Builder does not
explicitly build zlib.  By taking this decision, there is no need
to update the libpng project each time when there is a change in
the list of zlib source files.  After all, this list is private to
zlib, and applications (such as libpng) should not assume anything
about it.

If you wish to contribute a project that builds zlib under Borland
C++ Builder, please submit it to the zlib developers, not to the
libpng developers.

By default, the libpng project uses zlib as a static library.  If
you wish to use zlib as a DLL, please read the important notes from
the zlib DLL FAQ, found inside the zlib distribution.