[llvm] [llvm] Add CMake flag to compile out the telemetry framework (PR #124850)

[Jonas Devlieghere via llvm-commits]

JDevlieghere wrote:

> Quick question: why isn't using the existing option to disable the framework sufficient?

By the _existing option_, I assume you're referring to the `Telemetry::Config` struct? I can't speak for the original author on Discourse, but I would assume it's because it's much easier to verify statically that you don't have any telemetry code when it has been compiled out (e.g. you can run `strings` on the binary) compared to dynamically where you have to prove that code is never called. 

https://github.com/llvm/llvm-project/pull/124850