fix vectorization rule of diagonal-product
fix vectorization rule of diagonal-product

rotorliu/eigen,madlib/eigen_backup,madlib/eigen_backup,mjbshaw/Eigen,rotorliu/eigen,madlib/eigen_backup,mjbshaw/Eigen,mjbshaw/Eigen,madlib/eigen_backup,rotorliu/eigen,rotorliu/eigen,mjbshaw/Eigen