[clang] [Clang] Add __builtin_counted_by_ref builtin (PR #114495)

[Bill Wendling via cfe-commits]

bwendling wrote:

This is a new PR, because GitHub messed up. Here's the original: https://github.com/llvm/llvm-project/pull/102549

https://github.com/llvm/llvm-project/pull/114495