message: util: Make thread names shorter
  Thread names at the process level are limited by 15 characters. This
  commit ensures that name 'b-httpworker.42' will not be cropped.
diff: @@ -57,6 +57,6 @@ static void SetInternalName(std::string name) { }
  void util::ThreadRename(std::string&& name)
  {
  - SetThreadName(("bitcoin-" + name).c_str());
  + SetThreadName(("b-" + name).c_str());
  SetInternalName(std::move(name));
  }
  