Meta's Buck2 build system

Meta has announcedthe release of a new build system called Buck2.

While it shares some commonalities with other build systems (likeBuck1 and Bazel), Buck2 is a from-scratch rewrite. Buck2 features acomplete separation of the core and language-specific rules, withincreased parallelism, integration with remote execution andvirtual file systems, and a redesigned console output. All of thesechanges are aimed at helping engineers and developers spend lesstime waiting, and more time iterating on their code.