pthread_kill
int pthread_kill(pthread_t, int);
pthread_kill(main_thread, SIGINT);
RZ(pthread_kill(tester_thread, SIGUSR1));
ATF_REQUIRE(pthread_kill(thr, SIGINT) == 0);
pthread_kill(pthread_self(), sigval);
pthread_kill(t, SIGUSR1);
PTHREAD_REQUIRE(pthread_kill(th[i].id, SIGUSR1));