The actual swapchain implementation ignores the swap effect and always does a
copy anyway, but this makes it consistent with ddraw_attach_d3d_device().

Update ddraw_attach_d3d_device() for consistency.

This allows us to actually take the "override" parameter into account. Plain
back -> front flips will be detected in wined3d_surface_flip() and will still
be handled by wined3d_swapchain_present().