I would like to propose that we include `FileCheck` in the downloadable toolchains.
The downloadable toolchains are quite useful for people who are wanting to work on Swift projects that use FileCheck (llbuild, swift-integration-tests), but don't want to build everything from scratch. I would suggest it be located in '/usr/local/bin', to give some indication that it is a tool somewhat internal to the project.
Any objections? The gzipped tool comes to around 150KB, which is a drop in the bucket of our current ~200MB archives.