[Sema] refactor TypeDecl::isNoncopyable

In preparation for reporting whether the inverse marking on a TypeDecl
was inferred instead of explicit.

lib/SIL/IR/SILModule.cpp

@@ -680,7 +680,7 @@ lookUpFunctionInVTable(ClassDecl *Class, SILDeclRef Member) {
 
 SILFunction *
 SILModule::lookUpMoveOnlyDeinitFunction(const NominalTypeDecl *nomDecl) {
-  assert(nomDecl->isNoncopyable());
+  assert(nomDecl->canBeNoncopyable());
 
   auto *tbl = lookUpMoveOnlyDeinit(nomDecl);