Sizes of pthreads-win32 structs
-------------------------------
                     pthread_t    8
                ptw32_thread_t  152
               pthread_attr_t_   28
                        sem_t_   12
              pthread_mutex_t_   24
          pthread_mutexattr_t_    8
           pthread_spinlock_t_    8
            pthread_barrier_t_   36
        pthread_barrierattr_t_    4
                pthread_key_t_   16
               pthread_cond_t_   32
           pthread_condattr_t_    4
             pthread_rwlock_t_   28
         pthread_rwlockattr_t_    4
               pthread_once_t_   16
               ptw32_cleanup_t   12
             ptw32_mcs_node_t_   16
                   sched_param    4
-------------------------------