Remove bit that shouldn't be part of (rptN), and rewrite the handling of (even) and (pos_infinity) to uncover a missing (neg_infinity) modifier. Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10291>
Signed-off-by: Rob Clark <robdclark@chromium.org> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7997>