removing code for pre 10.6 systems

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77033 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
removing code for pre 10.6 systems

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77034 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775