[clang] [clang] remove ClassScopeFunctionSpecializationDecl (PR #66636)

[Shafik Yaghmour via cfe-commits]

================
@@ -4086,7 +4073,7 @@ FunctionDecl *Sema::SubstSpaceshipAsEqualEqual(CXXRecordDecl *RD,
   Decl *R;
   if (auto *MD = dyn_cast<CXXMethodDecl>(Spaceship)) {
     R = Instantiator.VisitCXXMethodDecl(
-        MD, nullptr, std::nullopt,
+        MD, nullptr,
----------------
shafik wrote:

```suggestion
        MD, /*TemplateParams=*/nullptr,
```

https://github.com/llvm/llvm-project/pull/66636