[clang] [llvm] [IR] Add flags operand to structured.gep (PR #200093)

[Krzysztof Drewniak via cfe-commits]

krzysz00 wrote:

@nhaehnle @piotrAMD Your thoughts? (this being the realization of the discussion we had at EuroLLVM a while back, or at least part 1 of it)

https://github.com/llvm/llvm-project/pull/200093