Since Zlib 1.2.10, it seems that zlib and png need to be paired
together. The UNIX 'configure' script has been updated to either use
system png and zlib libraries, or both as built-in libraries. This
shouldn't affect Windows (which uses both built-in anyway), but it
does require changes to OSX (which currently doesn't build at all).
The UNIX builds for Debian and Redhat/RPM now default to using the
builtin PNG and zlib libraries. This will ease issues at release
time, since we don't need to worry about those libraries being
present on the destination systems.
git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2054 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
