message: fix compile error on APPLE
diff: @@ -26,10 +26,7 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  #include "client_bw.h"
  #include "mutex.h"
  #include <memory>
  -
  -namespace std {
  - class thread;
  -}
  +#include <thread>
  class CounterWidthExtender
  {
  