Oops, correction re netCDF-4 external data representation

Greg,

I wrote, incorrectly, it turns out:

> Using XDR order for external data is the way we're currently doing it
> in netCDF-4.  One reason we did this was to simplify comparing the
> same data written on different platforms.

We're actually using native representations instead of XDR for
netcdf-4.  Sorry for the confusion.

--Russ