Do not print nulls in lists of derived types
Do not print nulls in lists of derived types

An earlier patch had disabled the null value check when printing lists
of derived types.  However, this could happen with a non-contiguous
list, e.g. only values 1, 4, and 8 explicitly set.

The check is now restored, and we do not print the null values.

marshallward/f90nml,marshallward/f90nml,honnorat/f90nml,honnorat/f90nml