[clang] [CIR] Add CIR x86 codegen builtins tests (PR #173726)

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MarwanTarik wrote:

Hello, yes, I remember removing those tests because they were causing the pipeline to fail. If I recall correctly, the methods corresponding to those tests hadn’t been implemented yet at the time of this PR, and it wasn't part of it. And I'm sorry for any confusion I caused.

https://github.com/llvm/llvm-project/pull/173726