This PR adds a default parallel implementation of `std::reverse_copy`
based on `std::reverse_iterator` + parallel `std::copy`.
Effectively it's a one-liner:
```c++
return _Copy()(__policy,
std::reverse_iterator<_BidirectionalIterator>(std::move(__last)),
std::reverse_iterator<_BidirectionalIterator>(std::move(__first)),
std::move(__result));
```
Included tests check that:
- Semantics of the function is correct.
- The function correctly SFINAE out when the first argument is not an
execution policy.
- The `nodiscard` policy is followed.
- The `noexcept` policy is followed.
- `static_assert` verifies iterators' categories (bidirectional and
forward).
Part of #99938.
---------
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
Michael G. KazakovandLouis Dionne
410a2a2363