Method setFields

Copy a list of fields into this structure, establishing its size. Should only be called once when constructing the type. Size is calculated from the fields unless a \b fixedSize (>0) is passed in. Alignment is calculated from fields unless a \b fixedAlign (>0) is passed in. \param fd is the list of fields to copy in \param fixedSize (if > 0) indicates an overriding size in bytes \param fixedAlign