GDK W32: Use SWP_NOOWNERZORDER everywhere it can be applied

GDK W32: Use SWP_NOOWNERZORDER everywhere it can be applied

There is no reason why we shouldn't pass this flag every time
Z-order changes. We have separate routines that are used to
maintain relative Z-order, so it should be completely OK to
pass SWP_NOOWNERZORDER to let the OS know that it shouldn't try
to maintain relative Z-order of the windows when raising them.