message: Fix portability issue with pthreads
  This change resolves the following issue:
  Only tested on OpenBSD 6.5/amd64
diff: #include <atomic>
  #include <thread>
  +#if (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
  +#include <pthread.h>
  +#include <pthread_np.h>
  +#endif
  +
  #include <util/threadnames.h>
  #ifdef HAVE_SYS_PRCTL_H
  