nir: gather all IO info from IO intrinsics

nir_io_add_const_offset_to_base will shrink num_slots, so it's better to
call it before nir_shader_gather_info.

Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6442>
1 file changed