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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> Should be fixed by https://github.com/llvm/llvm-project/commit/940f89255e4a3982d94dad57837e8e658092af78.

I quickly glanced through the other uses of setIsInBounds in LLVM; the one in CodeGenPrepare seems suspicious.

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