Enable wxComboBox::SetString() test in the widgets sample.

It was disabled because it wasn't implemented for wxGTK at some time in the
past -- but it is implemented now, so there is no reason to not allow testing
it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71315 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/widgets/combobox.cpp

@@ -481,11 +481,7 @@ void ComboboxWidgetsPage::OnButtonChange(wxCommandEvent& WXUNUSED(event))
     int sel = m_combobox->GetSelection();
     if ( sel != wxNOT_FOUND )
     {
-#ifndef __WXGTK__
         m_combobox->SetString(sel, m_textChange->GetValue());
-#else
-        wxLogMessage(wxT("Not implemented in wxGTK"));
-#endif
     }
 }