main: top of loop: sval = 0
main: calling sem_timedwait
thread: calling sem_timedwait with bogus tv_nsec
thread: sem_timedwait: errno = 22 strerror = Invalid argument
thread: calling sem_post
main: sem_timedwait: success
main: calling sem_post
main: top of loop: sval = 1
main: calling sem_timedwait
main: sem_timedwait: success
main: calling sem_post