path::iterator isn't a strictly conforming iterator. Specifically
it stashes the current element inside the iterator. This leads to
UB when used with reverse_iterator since it requires the element
to outlive the lifetime of the iterator.
This patch adds a static_assert inside reverse_iterator to disallow
"stashing iterator types", and it tags path::iterator as such a type.
Additionally this patch removes all uses of reverse_iterator<path::iterator>
within the tests.
llvm-svn: 300164
e02ed1c255