netcdf: Remove szip dependency

[eborisch (Eric A. Borisch)]

The szip port is not required by the hdf5-18 port anymore; it was moved into the +szip variant as it is not distributable and is not needed for the bulk of hdf5's functionality.

Removing this will make netcdf distributable as well.

[tenomoto (Takeshi Enomoto)]

I believe szip is almost a must with hdf5. I think I was told to make szip default in the past for user's convenience. I'm going to instruct users to add +szip with hdf5-18. hdf5-18 +szip is not redistributable, is it?

[eborisch (Eric A. Borisch)]

Not redistributable is the cleanest way to describe it. As I read it, the license for szip is convoluted and depends on if it is being used through HDF5 or not.

Taken from ​http://www.hdfgroup.org/doc_resource/SZIP/

szip is only required if you are actually reading or writing szip-compressed data. If it is needed, the user should install hdf5-18 +szip (which will build from source) before installing netcdf. The netcdf port itself shouldn't directly require szip (IMHO) as it is not directly using it, but only through the hdf5-18 port if it has been installed with +szip.

I haven't tested to see if a netcdf build against a non-szip enabled libhdf5 will function with a (locally compiled) szip-enabled libhdf5.

-Eric

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Licensing terms

The version of Szip distributed with HDF products is free for non-commercial use, which may occur in two sets of circumstances:

Non-commercial users may use the Szip software integrated with HDF products to both encode (compress) and decode (uncompress) data. This applies to educational and research applications.

Commercial users may use the software to decode any data. Further, they may use the software in internal activities that do not involve or result in the development of an Szip-based software product.

Commercial licenses are available for commercial users who wish to distribute an Szip-based software product or engage in commercial uses that are not allowed above. For further licensing information or to view a copy of the Szip copyright statement, see Commercial use terms and the copyright and license notice pertaining to Szip in HDF products.

[tenomoto (Takeshi Enomoto)]

I removed dependency to szip from netcdf, nco and hdf4. hdf4 has szip variant (r93151). How do you like that?

[MarcusCalhoun-Lopez (Marcus Calhoun-Lopez)]

I believe hdf4 still depends on szip.
Attached is a proposed solution (also fixes a typo).

[MarcusCalhoun-Lopez (Marcus Calhoun-Lopez)]

Cc Me!

[tenomoto (Takeshi Enomoto)]

Committed r93676.