At least on HPUX, select with delay.tv_sec = 0 and delay.tv_usec = 1000000

At least on HPUX, select with delay.tv_sec = 0 and delay.tv_usec = 1000000
does not lead to a one-second delay, but to an immediate EINVAL failure.
This causes CHECKPOINT to crash with s_lock_stuck much too quickly :-(.
Fix by breaking down the requested wait div/mod 1e6.