Avoid showing 2 tooltips simultaneously in wxMSW wxListCtrl

Only show the built-in control tooltips if we're not showing any custom
ones.

Closes https://github.com/wxWidgets/wxWidgets/pull/1500

Closes #10492.

include/wx/msw/listctrl.h

@@ -390,6 +390,9 @@ protected:
         { return MSWGetBestViewRect(width, -1).y; }
     virtual int DoGetBestClientWidth(int height) const wxOVERRIDE
         { return MSWGetBestViewRect(-1, height).x; }
+#if wxUSE_TOOLTIPS
+    virtual void DoSetToolTip(wxToolTip *tip) wxOVERRIDE;
+#endif // wxUSE_TOOLTIPS
 
     wxSize MSWGetBestViewRect(int x, int y) const;