nir: update nir_gather_info to only mark used array/matrix elements

nir: update nir_gather_info to only mark used array/matrix elements

This is based on the code from the GLSL IR pass however unlike the GLSL IR
pass it also supports arrays of arrays.

As well as implementing the logic from the GLSL IR pass we add some
additional intrinsic cases to catch more system values.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>