Hi Guix,

this patch enables HDF4 support in the netCDF package.

By the way, I noticed some error messages from doxygen during the 
build:

error: Problems running dot: exit code=127, command='dot', 
arguments='"/tmp/guix-build-netcdf-4.4.1.1.drv-0/netcdf-4.4.1.1/docs/html/datt_8c__incl.dot" 
-Tpng -o 
"/tmp/guix-build-netcdf-4.4.1.1.drv-0/netcdf-4.4.1.1/docs/html/datt_8c__incl.png"'
(these error are already in the present package, for example see 
http://hydra.gnu.org/build/1686038/log/raw ).

These errors don't cause the build to fail, and are related to 
html/pdf documentation, which is not installed anyway, as far is I 
can see.  So perhaps not very critical.

When I build the package myself in a “guix environment netcdf”, I 
can't reproduce the errors.

cheers,

Thomas