The vtkNetCDFCFReader allows you to specify the output type and makes
the best attempt to represent the data in that type.  Even though
sometimes the representation makes little sense (like storing an
unstructured grid in an extent-based data set like structured grids),
the reader should at least continue to be stable (see ParaView bug

There was a corner case in one of these nonsensical conversions where a
data array was read one past its end.  This change makes a different way
to create nonsense and avoids the bad array access.

Change-Id: Idc30bb9aa8474c1a67c36b22f05aa99428b1b37e