[clang] Reapply [Clang] Mark new as inaccessiblememonly if sane (PR #217652)

[Nikita Popov via cfe-commits]

nikic wrote:

Thanks for the report. I thought the code I was changing already handled that, but apparently it's EmitNewDeleteCall() that adds the `builtin` attribute for uses of `new` (as opposed to `::operator new`). This new logic should probably live there as well.

https://github.com/llvm/llvm-project/pull/217652