HEIMDAL_MUTEX_lock
#define HEIMDAL_MUTEX_lock(m) do { if ((*(m))++ != 0) abort(); } while(0)
#define HEIMDAL_MUTEX_lock(m) do { (void)(m); } while(0)
#define HEIMDAL_MUTEX_lock(m) mutex_lock(m)
#define HEIMDAL_MUTEX_lock(m) pthread_mutex_lock(m)