2d400db63c
`contiguous_iterator` requires the iterator type passed is either a pointer type or that the element type of the iterator is a complete object type. These constraints are not part of the current wording in defining the `contiguous_iterator` concept - adjust the concept to reflect this. Inspired from discussion at https://reviews.llvm.org/D108645. Reviewed By: #libc, ldionne Differential Revision: https://reviews.llvm.org/D108855