Add wxHAS_BITMAPTOGGLEBUTTON and test for it in the unit test.

Add wxHAS_BITMAPTOGGLEBUTTON and test for it in the unit test.

Not all ports define wxBitmapToggleButton class currently, so add a special
symbol which is defined only if this class is indeed available and test for it
in the unit test for this class.

This fixes the tests compilation under wxX11.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65706 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775