Auto merge of #32438 - kamalmarhubi:intoiterator-example, r=steveklabnik

style: Use `iter` for IntoIterator parameter names

This commit standardizes the codebase on `iter` for parameters with
IntoIterator bounds.

Previously about 40% of IntoIterator parameters were named `iterable`,
with most of the rest being named `iter`. There was a single place where
it was named `iterator`.

diff --cc src/libcore/iter.rs
Simple merge