Possibly wrong calculation

[Ganneff]

https://github.com/Ganneff/cpu1sec/blob/0642acf801be2ae0bd168482e6161c2309e18951/src/main.rs#L123-L143

That's possibly wrong (or the definition of CpuStat). We want to calculate the diff, but numbers are unsigned. Now, if new (other) is higher, this will fail (or not, in release builds Rust will hide the failure).