[clang] [Clang] Implement the 'counted_by' attribute (PR #76348)

[Bill Wendling via cfe-commits]

================
@@ -365,6 +365,10 @@ class DefaultFilterCCC final : public CorrectionCandidateCallback {
 template <class C>
 class DeclFilterCCC final : public CorrectionCandidateCallback {
 public:
+  explicit DeclFilterCCC(const IdentifierInfo *Typo = nullptr,
+                         NestedNameSpecifier *TypoNNS = nullptr)
----------------
bwendling wrote:

I was copying off of the other `CCC` classes. Perhaps it's because both arguments have default values?

Segfault seems to agree (https://stackoverflow.com/questions/4467142/why-is-explicit-allowed-for-default-constructors-and-constructors-with-2-or-more):

> One reason where it's needed is, if you have default arguments for the first parameter. The constructor becomes a default constructor, but can still be used as converting constructor

```
struct A {
  explicit A(int = 0); // added it to a default constructor
};
```


https://github.com/llvm/llvm-project/pull/76348