Update font of wxSpinCtrl when DPI changes

Fix position of spin control in wxSpinCtrlDouble after DPI change
The old size of the control was used to determine the position. Use GetBestSize
instead, which will return the correct size.

include/wx/msw/spinctrl.h

@@ -131,6 +131,7 @@ protected:
     virtual bool MSWOnNotify(int idCtrl, WXLPARAM lParam, WXLPARAM *result) wxOVERRIDE;
     virtual bool MSWOnScroll(int orientation, WXWORD wParam,
                              WXWORD pos, WXHWND control) wxOVERRIDE;
+    virtual void MSWUpdateFontOnDPIChange(const wxSize& newDPI) wxOVERRIDE;
 
     // handle processing of special keys
     void OnChar(wxKeyEvent& event);