[clang] [llvm] [SPIR-V] Implement SPV_KHR_untyped_pointers extension (PR #201233)

[Marcos Maronas via cfe-commits]

https://github.com/maarquitos14 commented:

In general, LGTM. I left a few comments, and I have two questions:

- Do we accept no indexes for *AccessChain? Should we add tests enforcing our decision?
- I think I've seen a test with nested arrays, and a test with nested structs, but none combining them. Should we add one?

https://github.com/llvm/llvm-project/pull/201233