with old gcc (bug 89), only include iostream in debug mode
with old gcc (bug 89), only include iostream in debug mode

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