Added wxUnusedVar for Borland and fixed 2 release mode warnings for Borland (patch #835707); Slight code cleanup.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@24508 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/vlbox.cpp

@@ -540,6 +540,7 @@ void wxVListBox::OnKeyDown(wxKeyEvent& event)
         default:
             event.Skip();
             current = 0; // just to silent the stupid compiler warnings
+            wxUnusedVar(current);
             return;
     }