Update for the 5.5 branch

Author: DougGregor

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2302,11 +2302,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     if (auto superclass = CD->getSuperclassDecl()) {
       // Actors cannot have superclasses, nor can they be superclasses.
       if (CD->isActor() && !superclass->isNSObject())
-        CD->diagnose(diag::actor_inheritance,
-                     /*distributed=*/CD->isDistributedActor());
+        CD->diagnose(diag::actor_inheritance);
       else if (superclass->isActor())
-        CD->diagnose(diag::actor_inheritance,
-                     /*distributed=*/CD->isDistributedActor());
+        CD->diagnose(diag::actor_inheritance);
     }
 
     // Force lowering of stored properties.