Well, GD failed most (maybe all) of its tests -- and then, at the urging of (I believe) Beatnik, I did the make install anyway, and it proceeded to work.
I don't know if that was because the script only called working things, or if the tests are borked, or what, and I don't care. I tested the output; it did indeed work.
Today is "do homework and finish testing code" day, and tomorrow is "hope car will get fixed and finish reading" day.
BTW, I seem to recall having the same sort of headaches a long time ago when I tried installing the GD module. IIRC, I started referring to GD as the "God Damned" module.