include/sem: Implement sem_trywait() using sem_wait() with 0 timeout

include/sem: Implement sem_trywait() using sem_wait() with 0 timeout

Because sem_trywait() does not unlock the waitlock if the counter is
greater than 1, the next caller will be left waiting until sem_post()
is executed.

This commit changes sem_trywait() to call sem_wait() with a timeout
of 0 seconds, since this issue does not affect sem_wait().