fixed VC++ warning (in release only)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@17853 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/widgets/slider.cpp

@@ -459,9 +459,7 @@ void SliderWidgetsPage::OnUpdateUIOtherSide(wxUpdateUIEvent& event)
 
 void SliderWidgetsPage::OnSlider(wxScrollEvent& event)
 {
-    long value = event.GetInt();
-
-    wxASSERT_MSG( value == m_slider->GetValue(),
+    wxASSERT_MSG( event.GetInt() == m_slider->GetValue(),
                   wxT("slider value should be the same") );
 
     wxEventType eventType = event.GetEventType();