[clang] [llvm] [clang][SPIR-V] Implement -fspv-preserve-interface (PR #196404)

[Diego Novillo via cfe-commits]

dnovillo wrote:

> > @bogner thanks for the review. Would you be able to submit the PR for me? I don't have write access to the repo. Thanks.
> 
> ~I'll do it.~
> 
> After the rebase son hlsl tests failed. @dnovillo could you check this ?
> 
> The windows failure look related to this PR.

Will do. Thanks for the heads up.

https://github.com/llvm/llvm-project/pull/196404