Also change the GTK implementation to use a separate wxInfoBarGTKImpl to store
its data, this object won't be even allocated if a generic implementation is
used under GTK.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62277 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775