fix a bug (factor of four in front of e12Csq) that entered with r1.54 on Sep04, 2015, -> requires updating results of lab_sea.hb87 (again)
fix a bug (factor of four in front of e12Csq) that entered with r1.54
on Sep04, 2015, -> requires updating results of lab_sea.hb87 (again)

altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h