This repository contains a script that takes a netcdf-c release, and remove all the files not used by chemfiles. This dramatically cuts down on the archive size, from 18Mib to ~500Kib.
The script also replaces the CMakeLists.txt, to adapt to chemfiles' build system.
Running the script (with Python >= 3.7) as python cleanup-netcdf-release.py
will produce the netcdf.tar.gz archive you want.