[llvm] [BOLT][NFC] Use brstack in guides and user outputs (PR #163950)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

I must have caused this failure:
- https://lab.llvm.org/buildbot/#/builders/217/builds/1004

Will send a fixup patch soon.

https://github.com/llvm/llvm-project/pull/163950