message: Update xz to 5.2.5, and switch the download link.
  This PR updates xz to 5.2.5, and switch the download link
  to use github instead as it is more stable.
diff: @@ -440,11 +440,11 @@ http_archive(
  http_archive(
  name = "xz",
  build_file = "//third_party:xz.BUILD",
  - sha256 = "b512f3b726d3b37b6dc4c8570e137b9311e7552e8ccbab4d39d47ce5f4177145",
  - strip_prefix = "xz-5.2.4",
  + sha256 = "0d2b89629f13dd1a0602810529327195eff5f62a0142ccd65b903bc16a4ac78a",
  + strip_prefix = "xz-5.2.5",
  urls = [
  - "https://storage.googleapis.com/mirror.tensorflow.org/tukaani.org/xz/xz-5.2.4.tar.gz",
  - "https://tukaani.org/xz/xz-5.2.4.tar.gz",
  + "https://storage.googleapis.com/mirror.tensorflow.org/github.com/xz-mirror/xz/archive/v5.2.5.tar.gz",
  + "https://github.com/xz-mirror/xz/archive/v5.2.5.tar.gz",
  ],
  )
  