[libc++] Deprecate std::iterator and remove it as a base class
C++17 deprecated std::iterator and removed it as a base class for all
iterator adaptors. We implement that change, but we still provide a way
to inherit from std::iterator in the few cases where doing otherwise
would be an ABI break.
Supersedes D101729 and the std::iterator base parts of D103101 and D102657.
Differential Revision: https://reviews.llvm.org/D103171
NOKEYCHECK=True
GitOrigin-RevId: 1055cb91b48280da0c42c5287b227cfdaae633b2
19 files changed