Futhark Packages

See https://github.com/infinisil/futharknixdemo

This is a small artificial packagification of https://github.com/diku-dk/futhark-benchmarks/tree/master/misc/heston

Main files are:

• default.nix - scope definition of the package set (and utils)
• buildFuthark.nix - definition of a function to build futhark packages
• futharkSrc.nix - builder for combining dependencies into a single path

The heston.nix file uses 3 other packages as a dependency. This heston package is then used by the futharknixdemo repository.

See the comments in the files as well.