[clang] Reland "[clang] Add nuw attribute to GEPs (#105496)" (PR #107257)

[Sam Clegg via cfe-commits]

sbc100 wrote:

Perhaps yes.  Do you know of any way to reduce the input program into something we can try to inspect.   The preprocessed C++ file is over 100,000 lines :-/

https://github.com/llvm/llvm-project/pull/107257