Class B3

tests/cppunit/status_test.cc:187–190

    std::string b;
  };
  struct B3 {
    char a;
    A b;
  };
  static_assert(sizeof(StatusOr<char>) == sizeof(B1));
  static_assert(sizeof(StatusOr<int>) == sizeof(B1));
  static_assert(sizeof(StatusOr<void *>) == sizeof(B1));