message: Update pcre library to 8.42.
  This fix updates pcre library 8.39 to 8.42.
  Pcre 8.39 was released in 14-June-2016, which is quite old.
diff: @@ -393,12 +393,12 @@ def tf_workspace(path_prefix="", tf_repo_name=""):
  tf_http_archive(
  name = "pcre",
  - sha256 = "ccdf7e788769838f8285b3ee672ed573358202305ee361cfec7a4a4fb005bbc7",
  + sha256 = "69acbc2fbdefb955d42a4c606dfde800c2885711d2979e356c0636efde9ec3b5",
  urls = [
  - "https://mirror.bazel.build/ftp.exim.org/pub/pcre/pcre-8.39.tar.gz",
  - "http://ftp.exim.org/pub/pcre/pcre-8.39.tar.gz",
  + "https://mirror.bazel.build/ftp.exim.org/pub/pcre/pcre-8.42.tar.gz",
  + "http://ftp.exim.org/pub/pcre/pcre-8.42.tar.gz",
  ],
  - strip_prefix = "pcre-8.39",
  + strip_prefix = "pcre-8.42",
  build_file = clean_dep("//third_party:pcre.BUILD"),
  )
  