[llvm] [ExtendLifetimes] Implement llvm.fake.use to extend variable lifetimes (PR #86149)

[Tobias Hieta via llvm-commits]

tru wrote:

Since python is already a dependency for running the tests I don't see a problem with it. While I am not sure we have tests implemented in python for clang, lldb has a lot of them so it's not unprecedented. I am interested in hearing what the objections would be in this case. 

https://github.com/llvm/llvm-project/pull/86149