Repeatable Cross-GCC Toolchain Builds with Nix

TwoSix utilized Nix to create a repeatable GCC cross toolchain build for the OpenRisc architecture, which is used in the Allwinner A64 chip's PMC. Nix ensures repeatability by hashing sources, fixing build times, and storing successful builds in a cache, making it more reliable than Docker for this task. The post includes a detailed Nix build script for setting up the toolchain.