Start bisecting GetAs() wxAny test itself.

This is the test that results in memory corruption in wxOSX PPC builds, try
to find out where exactly does this happen.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73955 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775