Merge pull request #2694 from ludovic-henry/fix-sleep-overflow

Merge pull request #2694 from ludovic-henry/fix-sleep-overflow

[threads] Fix mono_thread_info_sleep overflow

This overflow would happen of the machine was up for more than 29 days, leading to an overflow in the value returned by mono_100ms_ticks.

The simplest solution is simply to resort to mono_100ns_ticks which would only overflow after more than 29247 years. So even the platform implement this value as the time since 0000-00-00 00:00:00, we still have more than 27000 years if front of us. It's also highly unlikely that we would overflow the `end' value when adding `ms', as that would mean we are in the last 29 days of that 29247 years.

@monojenkins merge