Disable wxEvtHandler::CallAfter() for VC6, it's too broken for it.

There is no clear way to implement wxRemoveRef() for VC6 so just disable it,
and CallAfter() as it relies on it, for this compiler.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72743 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/event.h

@@ -519,6 +519,9 @@ public:
 
          Note that currently only up to 2 arguments can be passed.
 
+         @note This method is not available with Visual C++ 6 which doesn't
+               have the required support for C++ templates to implement it.
+
          @since 2.9.5
      */
     template<typename T, typename T1, ...>