_mutex_held
#define MUTEX_HELD(m) _mutex_held((mutex_t *)(m))
#define MUTEX_HELD(m) _mutex_held((mutex_t *)(m))
#define pthread_mutex_isowned_np(x) _mutex_held(x)
#define MUTEX_HELD(x) _mutex_held(x)
int _mutex_held(void *); /* mutex_t or pthread_mutex_t */