[llvm] [profcheck] Add heuristical profile metadata for lowering table-based cttz. (PR #161898)

[Mircea Trofin via llvm-commits]

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mtrofin wrote:

is it necessary to modify all the tests, or is checking in one case sufficient? e.g. just modify `@ctz1`.

If, later, the behavior of AggressiveInstCombine is such that other cases are introduced and that leads to !prof elision - the profcheck build bot will catch them.

https://github.com/llvm/llvm-project/pull/161898