color-lcms: cmsMAT3 is row-major after all

Found out in https://github.com/mm2/Little-CMS/issues/483



This should be a complete no-op change, but there is one difference.
Previously matrix_inf_norm() summed over rows. Now it sums over columns
as it should be. This shouldn't hurt because it is only used to identify
identity matrices. The bug was actually in is_identity_matrix_stage()
because it deliberately passed what was assumed to be a transpose of the
matrix.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>