message: Update gflags from to v2.2.1
  This fix bumps gflags from to the latest versioned
  release of v2.2.1
diff: @@ -384,11 +384,11 @@ def tf_workspace(path_prefix="", tf_repo_name=""):
  tf_http_archive(
  name = "com_github_gflags_gflags",
  urls = [
  - "https://mirror.bazel.build/github.com/gflags/gflags/archive/f8a0efe03aa69b3336d8e228b37d4ccb17324b88.tar.gz",
  - "https://github.com/gflags/gflags/archive/f8a0efe03aa69b3336d8e228b37d4ccb17324b88.tar.gz",
  + "https://mirror.bazel.build/github.com/gflags/gflags/archive/v2.2.1.tar.gz",
  + "https://github.com/gflags/gflags/archive/v2.2.1.tar.gz",
  ],
  - sha256 = "4d222fab8f1ede4709cdff417d15a1336f862d7334a81abf76d09c15ecf9acd1",
  - strip_prefix = "gflags-f8a0efe03aa69b3336d8e228b37d4ccb17324b88",
  + sha256 = "ae27cdbcd6a2f935baa78e4f21f675649271634c092b1be01469440495609d0e",
  + strip_prefix = "gflags-2.2.1",
  )
  tf_http_archive(
  