Method increment_conn

plugin/handler_socket/client/hstest.cpp:150–156

    atomic_exchange_and_add(&count, c);
  }
  void increment_conn(unsigned int c) const volatile {
    atomic_exchange_and_add(&conn_count, c);
    while (wait_conn != 0 && conn_count < wait_conn) {
      sleep(1);
    }
    // fprintf(stderr, "wait_conn=%ld done\n", wait_conn);
  }
};

struct hstest_thread {