[clang] treat deduced-as-dependent as undeduced for constant template parameters (#161099)

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