9fbbe75fd7
Fix `array::IntoIter::fold` to use the optimized `Range::fold` It was using `Iterator::by_ref` in the implementation, which ended up pessimizing it enough that, for example, it didn't vectorize when we tried it in the <https://rust-lang.zulipchat.com/#narrow/stream/257879-project-portable-simd/topic/Reducing.20sum.20into.20wider.20types> conversation. Demonstration that the codegen test doesn't pass on the current nightly: <https://rust.godbolt.org/z/Taxev5eMn>