message: [crispy] logstore: API convenience improvements
diff: @@ -165,8 +165,8 @@ class Category
  void set_sink(logstore::Sink& s) { _sink = s; }
  logstore::Sink& sink() const noexcept { return _sink.get(); }
  - MessageBuilder build(source_location location) const { return MessageBuilder(*this, location); }
  - MessageBuilder operator()(source_location location) const { return MessageBuilder(*this, location); }
  + MessageBuilder build(source_location location = source_location::current()) const { return MessageBuilder(*this, location); }
  + MessageBuilder operator()(source_location location = source_location::current()) const { return MessageBuilder(*this, location); }
  static std::string default_formatter(MessageBuilder const& _message);
  