Automate version comparison

[ikabadzhov]

This is a small script to compare performance between 2 different patches/commits. The script will take care of building 2 ROOT versions and running the desired benchmarks. And finally https://github.com/google/benchmark/blob/main/tools/compare.py compares both.

[vgvassilev]

Thanks for working on this. That's really exciting. Could you add documentation/script which demonstrates how to use these tools to do git bisect based on a performance regression?

[eguiraud]

Hi Vassil,

Could you add documentation/script which demonstrates how to use these tools to do git bisect based on a performance regression?

This is not something you can do with this script as it is, might be something that can be built on top in a future PR