[clang] [Headers][X86] VisitCallExpr constexpr immediate shifts (#154293) (PR #155542)

[Justin Riddell via cfe-commits]

Arghnews wrote:

Have addressed feedback @RKSimon

Will wait on https://github.com/llvm/llvm-project/pull/155891 then I can refactor this based on what goes in (and squash)

Let me know if I should do otherwise or anything else needs doing on this, thanks

https://github.com/llvm/llvm-project/pull/155542