Possibly update g2clib to 1.6.0

[Kurt Schwehr]

There is a new version of g2clib out recently. There are a nubmer of fixes that we might or might not have in GDAL. It also looks like we should really be getting fixes back to NOAA NCEP folks (Gilbert and Vuong?). I have already pinged NCEP.NCO.GRIB@… about getting the library better documented. There is no listed license and there is no copyright (or lack of copyright) stated in the tar.

• ​http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2/
• ​http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2/g2clib-1.6.0.tar

I don't think this is super important, but might as well start getting things clean in upstream.

[Even Rouault]

Done per r40752

[Kurt Schwehr]

Thanks!