You are most probably correct and the product may be broken.
However, the current state of the art is that this repository became just a placeholder for some added programs, but not the core ggnfs package. The new tools have better performance, and if you want to build ggnfs only for historical reasons, then your best bet would probably be to build libgmp v.4, as well. There used to be times (a few years ago) when some tools (like pol5) were still used while the main source was largely abandoned, but now even pol5 is obviated by msieve. C.Monico once announced that he was re-writing the ggnfs package into another version, but this was never published.
If your interest is rather in building the modern version of the tools, then you need the following components:
1. factMsieve.pl script (or factmsieve.py python script - can be found on this forum)
2. msieve - see
http://sourceforge.net/projects/msieve/ (Use the stable revision 923)
3. the Kleinjung-Franke lattice sievers in
this branch
4. (optional)
remdups utility