[llvm] [NFC][SPIRV] Fix for selectExtInst to be able to process intrinsics (PR #110864)

[Cooper Partin via llvm-commits]

https://github.com/coopp approved this pull request.

Looks good to me.  I didn't see any test changes in this PR, so I assume this change will be covered by existing tests?

https://github.com/llvm/llvm-project/pull/110864