When we moved the bulk of glsl_type to C, these globals were
kept to avoid changes to compiler/glsl code in the MR. Now that
landed, change the code to use the actual bultins directly.
Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26658>