You need to have the GFC library installed on your system to build
some of the scenery generation tools, otherwise, some of the tools will fail
to build.

You can get the original library from:

    http://www.geog.psu.edu/~qian/gfc/index.html

However, until LJ rolls out the next release with a couple key fixes, 
I recommend you grab a copy with a couple modifications I have made 
which should eliminate several gfc build problems:

    ftp://ftp.flightgear.org/pub/fgfs/Source/gfc-0.8.8.1a.tar.gz