remove wxOVERRIDE, forgot that it's trunk only

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76366 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
fix building or running on GTK < 2.14 after r76365

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76367 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775