Fix crash with newer OS X builds running on older.

Use built-in zlib sources instead of system zlib. Backport of trunk
r76382, r76383, and r76385.

Closes #16192.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@77954 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775