Add optional argument to FMS2 version of get_field_size#64

marshallward merged 3 commits into

NOAA-GFDL:dev/gfdlNOAA-GFDL/MOM6:dev/gfdlfrom

MJHarrison-GFDL:fms2_fldszMJHarrison-GFDL/MOM6:fms2_fldszCopy head branch name to clipboard