That one might be on me for failing to gut all the icarus related stuff out of compac drivers. I've been collecting some small things that need to be repaired and I'll probably post an updated version soon. As far as your fix where you deleted the duplicate lines that's fine unless you don't build with --enable-icarus, because there are still apparently references to opt_anu_freq in driver-gekko.c. As I said, I have them cleaned up in my current working version and should have it out for you guys soon. I'll try to test with the u2 as well.
Thanks for looking into this. There are other compile problems with usbutils.c, which I've just worked through. Now I'm seeing problems with driver-gekko.c.
Unfortunately I'm out of time for the next few hours. So I won't be able to poke at this anymore.
But none of these are difficult problems. Looks like it's just some clean up to dis-entangle your gekko implementation from the same named code and variables for icarus.
If you get a clean build before I do, I'd be happy to take your source updates and rebuild for the Pi.
I've already got most of it done, I just need to test it thoroughly before I post it.