Fix bug in symmetric rank-2 update for row-major matrices (bug 144).
Fix bug in symmetric rank-2 update for row-major matrices (bug 144).

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