Rollup merge of #22299 - bluss:range-64-is-not-exact-size, r=alexcrichton

 Fixes #22047

`Range<u64>` and `Range<i64>` may be longer than usize::MAX on 32-bit
platforms, and thus they cannot fulfill the protocol for
ExactSizeIterator. We don't want a nonobvious platform dependency in
basic iterator traits, so the trait impl is removed.

The logic of this change assumes that usize is at least 32-bit.

This is technically a breaking change; note that `Range<usize>` and
`Range<isize>` are always ExactSizeIterators.

[breaking-change]