[llvm] [NFC][BOLT] Make file-local cl::opt global variables static (PR #126472)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Were the earlier check failures (before the last force-push) related to the fact that ContinuityStats was renamed to ProfileQualityStats?

Would it worth to make the cl::opts in there static too, before merging?

https://github.com/llvm/llvm-project/pull/126472