[llvm] [BOLT] Add auto parsing for Linux kernel .altinstructions (PR #95068)

[Davide Italiano via llvm-commits]

https://github.com/dcci approved this pull request.

Somewhat sad we have to "guess" and there's no obvious way, but other than that, this is the best we can do, so LGTM.

https://github.com/llvm/llvm-project/pull/95068