Fixed wxDataViewCtrl::Set{Foreground,Background}Colour() to work under GTK too.

Implement DoApplyWidgetStyle() in wxGTK version of wxDataViewCtrl to propagate
the main window style to the GtkTreeView which is what the user mostly sees.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62154 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/dataview.h

@@ -447,6 +447,8 @@ protected:
     virtual void DoSetExpanderColumn();
     virtual void DoSetIndent();
 
+    virtual void DoApplyWidgetStyle(GtkRcStyle *style);
+
 private:
     friend class wxDataViewCtrlDCImpl;
     friend class wxDataViewColumn;