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.

The original web page no longer exists, but the url *used* to be:

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

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-0.8.8.1b.tar.gz