4e986568b8
Fixes the two-sided-lighting and vertex-program-two-side piglit tests on Panfrost. v2: Use an existing variable for gl_FrontFacing if present. Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Reviewed-by: Rob Clark <robdclark@chromium.org> Tested-by: Urja Rannikko <urjaman@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5915>