adapting xcode build templates and config file to built-in zlib sources, see #16192

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76382 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
adding built-in zlib sources, see #16192

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76383 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775