don't crash when destroying a not initialized socket (patch 1489095)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39404 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/gsockmsw.cpp

@@ -335,6 +335,7 @@ void GSocketGUIFunctionsTableConcrete::Destroy_Socket(GSocket *socket)
 {
   /* Remove the socket from the list */
   EnterCriticalSection(&critical);
+  if ( socket->IsOk() )
       socketList[(socket->m_msgnumber - WM_USER)] = NULL;
   LeaveCriticalSection(&critical);
 }