When we ship LLVM 16, <ranges> won't be considered experimental anymore.
We might as well do this sooner rather than later.
Differential Revision: https://reviews.llvm.org/D132151
All supported compilers that support C++20 now support concepts. So, remove
`_LIB_LIBCPP_HAS_NO_CONCEPTS` in favor of `_LIBCPP_STD_VER > 17`. Similarly in
the tests, remove `// UNSUPPORTED: libcpp-no-concepts`.
Differential Revision: https://reviews.llvm.org/D121528
Since we officially don't support several older compilers now, we can
drop a lot of the markup in the test suite. This helps keep the test
suite simple and makes sure that UNSUPPORTED annotations don't rot.
This is the first patch of a series that will remove annotations for
compilers that are now unsupported.
Differential Revision: https://reviews.llvm.org/D107787
Louis Dionne