[clang] [webkit.RefCntblBaseVirtualDtor] Make ThreadSafeRefCounted not generate warnings (PR #107676)

[Ryosuke Niwa via cfe-commits]

rniwa wrote:

> Looks like you're putting no restrictions on what the opaque function is. This may cause some false negatives but it's probably ultimately ok, but it might be a good idea to confirm.

Yes, we're not putting any requirement for the functions for now.

https://github.com/llvm/llvm-project/pull/107676