[libcxxabi] [lldb] [compiler-rt] [mlir] [flang] [libc] [clang-tools-extra] [llvm] [libcxx] [lld] [clang] [libc++][ranges] Implement ranges::contains_subrange (PR #66963)

[Hristo Hristov via cfe-commits]

H-G-Hristov wrote:

Just a gentle reminder. You should probably also update the release notes, the status page and the feature test macro: `#define __cpp_lib_ranges_contains 20XXXXL // also in <algorithm>`

https://github.com/llvm/llvm-project/pull/66963