Changed as per JM's suggestions.  Only enthalpy (Qice1 and Qice2) defaults to non-zero values when it is not read-in.  Fixed problem with threaded code.
Changed as per JM's suggestions.  Only enthalpy (Qice1 and Qice2) defaults
to non-zero values when it is not read-in.  Fixed problem with threaded code.

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