[llvm] [X86][GlobalISel] Use GIntrinsic during custom intrinsic selection (PR #83498)

[Evgenii Kudriashov via llvm-commits]

e-kud wrote:

@tschuett @arsenm thank you for the review! The PR with new intrinsic opcodes has been merged instead: https://github.com/llvm/llvm-project/pull/84941

https://github.com/llvm/llvm-project/pull/83498