[llvm] [BOLT] Modify MCPlus annotation internals. NFCI. (PR #70412)

[Vladislav Khmelevsky via llvm-commits]

yota9 wrote:

Nice @maksfb Thank you! It shall speed up golang processing time significantly (probably lowering memory consumption too), shall try it when we would have a free time :)

https://github.com/llvm/llvm-project/pull/70412