Add wxMenu::MSWDetachHMENU().

Make it possible to pass ownership of a wxMenu to win32.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76722 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/menu.cpp

@@ -352,7 +352,7 @@ wxMenu::~wxMenu()
     // we should free Windows resources only if Windows doesn't do it for us
     // which happens if we're attached to a menubar or a submenu of another
     // menu
-    if ( !IsAttached() && !GetParent() )
+    if ( m_hMenu && !IsAttached() && !GetParent() )
     {
         if ( !::DestroyMenu(GetHmenu()) )
         {