[clang] treat deduced-as-dependent as undeduced for cosntant template parameters

The AutoType's deduced-as-dependent mechanism is not really used for constant
template parameters, but this is currently harmless to ignore because when
dealing which such types, they will have been transformed, turning them back to
plain undeduced AutoTypes.

This should be NFC for current main users, but #141776
will depend on this.

Author: mizvekov

clang/lib/Sema/SemaTemplate.cpp

@@ -7102,7 +7102,7 @@ ExprResult Sema::CheckTemplateArgument(NamedDecl *Param, QualType ParamType,
 
   // If the parameter type somehow involves auto, deduce the type now.
   DeducedType *DeducedT = ParamType->getContainedDeducedType();
-  bool IsDeduced = DeducedT && !DeducedT->isDeduced();
+  bool IsDeduced = DeducedT && DeducedT->getDeducedType().isNull();
   if (IsDeduced) {
     // When checking a deduced template argument, deduce from its type even if
     // the type is dependent, in order to check the types of non-type template