WaitTimeoutResult Example does not exhibit timeout

[stevedonovan]

This example does not exhibit the desired behaviour:

https://doc.rust-lang.org/beta/std/sync/struct.WaitTimeoutResult.html

In the thread, the mutex is locked before waiting and then setting the condition, so wait_timeout waits until the condition is set (try changing that 20 ms to 1000 ms for dramatic effect). The sleep should be before the lock and notify.