System.NullReferenceException in thrown in ZeroMeasurementAnalyser with Android

[BraedenLS]

When the ZeroMeasurementAnalyser runs a report on a machine not using an OS with a supported "CpuDetector" it throws a null reference exception. This occurs on the line var currentFrequency = summary.HostEnvironmentInfo.Cpu.Value.MaxFrequency();, because Cpu.Value is null when using that OS.

[timcassell]

We need a new CpuDetector for Android. https://github.com/dotnet/BenchmarkDotNet/tree/2b6d7c796b5ba667c4729aabc1baa1181c556ef7/src/BenchmarkDotNet/Detectors

But we should probably gracefully handle platforms that we don't explicitly support anyway.