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

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

Maybe the patch introduced some miscompile?
The patch affects only clang, but failing tests are LLVM, but tools compiled with patched clang with UBSAN enabled.

Also there are branches checking sanitizers.

https://github.com/llvm/llvm-project/pull/105496