message: Harmonize line_builder::operator<< implementations
diff: @@ -236,17 +236,11 @@ logger::line_builder::line_builder() {
  logger::line_builder& logger::line_builder::
  operator<<(const local_actor* self) {
  - if (!str_.empty() && str_.back() != ' ')
  - str_ += " ";
  - str_ += self->name();
  - return *this;
  + return *this << self->name();
  }
  logger::line_builder& logger::line_builder::operator<<(const std::string& str) {
  - if (!str_.empty() && str_.back() != ' ')
  - str_ += " ";
  - str_ += str;
  - return *this;
  + return *this << str.c_str();
  }
  logger::line_builder& logger::line_builder::operator<<(string_view str) {
  @@ -257,17 +251,15 @@ logger::line_builder& logger::line_builder::operator<<(string_view str) {
  }
  logger::line_builder& logger::line_builder::operator<<(const char* str) {
  - if (!str_.empty())
  + if (!str_.empty() && str_.back() != ' ')
  str_ += " ";
  str_ += str;
  return *this;
  }
  logger::line_builder& logger::line_builder::operator<<(char x) {
  - if (!str_.empty())
  - str_ += " ";
  - str_ += x;
  - return *this;
  + const char buf[] = {x, '\0'};
  + return *this << buf;
  }
  std::string logger::line_builder::get() const {
  