Fix handling of extra-libs, extra-includes in Setup.hs

[rdnetto]

This PR modifies Setup.hs to correctly handle --extra-include-dirs and --extra-lib-dirs.
Failing to do so breaks compilation under Nix.

[tmcdonell]

Thanks!

Question: has nix not worked this entire time (I thought it did?) or did something change recently in the nix world?

[tmcdonell]

Do any of the other cuda packages need this fix as well?

[rdnetto]

Question: has nix not worked this entire time (I thought it did?) or did something change recently in the nix world?

I suspect it hasn't been working this entire time - without the extra-libs, there would have been no way to find nvidia-x11.
I only started using Nix recently though, so this is pure conjecture.

Do any of the other cuda packages need this fix as well?

With this change, all of cuda's dependency now build under Nix. (Admittedly this may simply be because they have no C dependencies). I haven't been able to compile accelerate* under Nix yet, but that's for a different reason (Nix doesn't contain the latest versions of each library, and the ones it does don't satisfy the version bounds). If further changes are required, I'll be happy to raise a PR for them once I figure out what they are.

[tmcdonell]

Sounds good to me. Uploaded as cuda-0.9.0.2.