fix #138: const bool is (rightly) not considered a compile-time constant by ICC, use enum.
fix #138: const bool is (rightly) not considered a compile-time constant by ICC, use enum.

TSC21/Eigen,toastedcrumpets/eigen,ROCmSoftwarePlatform/hipeigen,Zefz/eigen,TSC21/Eigen,TSC21/Eigen,toastedcrumpets/eigen,pasuka/eigen,pasuka/eigen,ROCmSoftwarePlatform/hipeigen,pasuka/eigen,ritsu1228/eigen,ritsu1228/eigen,Zefz/eigen,ROCmSoftwarePlatform/hipeigen,ritsu1228/eigen,toastedcrumpets/eigen,TSC21/Eigen,pasuka/eigen,Zefz/eigen,ritsu1228/eigen,ritsu1228/eigen,pasuka/eigen,Zefz/eigen,ROCmSoftwarePlatform/hipeigen,toastedcrumpets/eigen