fix compilation with icc. Anyway, the use of an enum instead of a 'const bool' is more consistent with the code around.
fix compilation with icc. Anyway, the use of an enum instead of a
'const bool' is more consistent with the code around.

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