[clang] [lldb] [Clang] Improve Sema diagnostic performance for __builtin_counted_by_ref (PR #116719)

[Bill Wendling via cfe-commits]

bwendling wrote:

> I think this might honestly be fine the way it is now

Yeah. It's going kind of the opposite way from what you suggested with the placeholder, just instead of allowing for different uses at various places in Sema we disallow without using the placeholder.

https://github.com/llvm/llvm-project/pull/116719