branches: 1.2.6;
Calibrate the amount of time that a sleep() requires, and use that
interval instead of assuming that there are exactly 1000 real-time-clock
milliseconds per second! On some ports when running under qemu, there
can be twice as many RTC milliseconds as expected.

This is part 2 of the changes required to make the libevent tests work
on port-amd64 under qemu.