These files are unpacked in the parent directory for the package; i.e. they
will create a diretory nfextern with only source (-src) or with source
and binaries.

The source is for V2.15 and the binaries are linked against V2.15.  So
for V2.14 or earlier you must use the binaries and can't build yourself.
If you want to build from source contact valdes@noao.edu.