Emit getelementptr inbounds nuw for pointer::add() Lower pointer::add (via intrinsic::offset with unsigned offset) to getelementptr inbounds nuw on LLVM versions that support it. This lets LLVM make use of the pre-condition that the offset addition does not wrap in an unsigned sense. Together with inbounds, this also implies that the offset is non-negative. Fixes https://github.com/rust-lang/rust/issues/137217.