f9b03cf405
This was enabled by default in nir_opt_varyings, but vc4 can't handle when shader outputs write Y but not X. Add an option for it and enable it only for the driver that benefits from it. Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32174>