[clang] [BoundsSafety][Sema] Allow counted_by and counted_by_or_null on pointers where the pointee type is incomplete but potentially completable (PR #106321)

[Erich Keane via cfe-commits]

================
@@ -3343,6 +3363,8 @@ class CountAttributedType final
   static bool classof(const Type *T) {
     return T->getTypeClass() == CountAttributed;
   }
+
+  StringRef GetAttributeName(bool WithMacroPrefix) const;
----------------
erichkeane wrote:

```suggestion
  StringRef getAttributeName(bool WithMacroPrefix) const;
```

Also a little concerning how specialized this is, rather than being part of how this type is printed.

https://github.com/llvm/llvm-project/pull/106321