Warning fixes found under hardest mode of OpenWatcom. Seems clean in Borland, MinGW and DMC.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29813 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/cmdproc.h

@@ -30,7 +30,7 @@ class WXDLLEXPORT wxCommand : public wxObject
 {
 public:
     wxCommand(bool canUndoIt = false, const wxString& name = wxEmptyString);
-    ~wxCommand();
+    ~wxCommand(){};
 
     // Override this to perform a command
     virtual bool Do() = 0;