modifications of library build scripts

[lars2015]

Suggestions to modify the library build script:

• [x] Limit the set of libraries built with the default option/selection to those that are mandatory for building the model (i.e. GSL, HDF5, netCDF, and zlib). Optional libraries (thrustsort, zfp, zstd, KPP) should only be compiled if the users selects them. This avoids initial problems installing MPTRAC if the library build processes are failing. (suggested by @laomangio)

• [ ] Consider integrating the libraries as git submodules rather than adding the source packages to the MPTRAC git repository. (suggested by @hydrogencl )

[hydrogencl]

The first issue is done by the commit 246b3fe.