backported wxSizer::ComputeFittingClientSize() and ComputeFittingWindowSize() to 2.8

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@52331 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/sizer.h

@@ -562,6 +562,11 @@ public:
 
     virtual void Layout();
 
+#if wxABI_VERSION >= 20808
+    wxSize ComputeFittingClientSize(wxWindow *window);
+    wxSize ComputeFittingWindowSize(wxWindow *window);
+#endif
+
     wxSize Fit( wxWindow *window );
     void FitInside( wxWindow *window );
     void SetSizeHints( wxWindow *window );