this alignment matches what nir_lower_scratch_to_var wants. this is not correctness bearing but it mitigates stats regressions. Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32529>