[llvm] Add support for SPIR-V extension: SPV_INTEL_function_pointers (PR #80759)

[Michal Paszkowski via llvm-commits]

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

@VyacheslavLevytskyy Thank you for the patch! LGTM! Verified -- the patch does not influence OpenCL CTS pass rate.

https://github.com/llvm/llvm-project/pull/80759