pthread_rwlock_trywrlock
int pthread_rwlock_trywrlock(pthread_rwlock_t *);
__strong_alias(__libc_rwlock_trywrlock,pthread_rwlock_trywrlock)
if (pthread_rwlock_trywrlock(&rw->pthrw) != 0)
rv = pthread_rwlock_trywrlock(&rw->pthrw);
ATF_REQUIRE_EQ(pthread_rwlock_trywrlock(&lk), EBUSY);