Some of the calendar types have landed before, this adds the missing
set. Note this does not complete the implementation of the chrono
formatters.
This removes the `chrono` header for some transitive include in C++17
mode. This is needed to avoid inclusion cycles.
Partially implements:
- P1361 Integration of chrono with text formatting
- P2372 Fixing locale handling in chrono formatters
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D137022
105fef5dca