ir_to_mesa: Add each relative address to the previous
This fixes many cases of accessing arrays of matrices using
non-constant indices at each level.
Fixes i965 piglit:
vs-temp-array-mat[234]-index-col-rd
vs-temp-array-mat[234]-index-col-row-rd
vs-temp-array-mat[234]-index-col-wr
vs-uniform-array-mat[234]-index-col-rd
Fixes swrast piglit:
fs-temp-array-mat[234]-index-col-rd
fs-temp-array-mat[234]-index-col-row-rd
fs-temp-array-mat[234]-index-col-wr
fs-uniform-array-mat[234]-index-col-rd
fs-uniform-array-mat[234]-index-col-row-rd
fs-varying-array-mat[234]-index-col-rd
fs-varying-array-mat[234]-index-col-row-rd
vs-temp-array-mat[234]-index-col-rd
vs-temp-array-mat[234]-index-col-row-rd
vs-temp-array-mat[234]-index-col-wr
vs-uniform-array-mat[234]-index-col-rd
vs-uniform-array-mat[234]-index-col-row-rd
vs-varying-array-mat[234]-index-col-rd
vs-varying-array-mat[234]-index-col-row-rd
vs-varying-array-mat[234]-index-col-wr
Reviewed-by: Eric Anholt <eric@anholt.net>