re-enable usage of ProductBase::m_result and workaround a compilation failure when m_result is too large but unused
re-enable usage of ProductBase::m_result and workaround a compilation failure when m_result is too large but unused

--HG--
branch : 3.2

robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen,robustrobotics/eigen