[llvm-branch-commits] [libcxx] [libc++] Adjust the version of __cpp_lib_ranges in C++20 mode (PR #109324)

[A. Jiang via llvm-branch-commits]

frederick-vs-ja wrote:

I guess 6f6422f4a2b8647a59936c131e50a79906d89510 and cdd608b8f0ce090b3568238387df368751bdbb5d should also be cherry-picked. @tru @ldionne 

https://github.com/llvm/llvm-project/pull/109324