overload for fail state label of ext unsigned type

alib2data/src/label/FailStateLabel.h

@@ -76,6 +76,11 @@ inline object::Object FailStateLabel::instance < object::Object > ( ) {
 	return object::Object ( FailStateLabel ( ) );
 }
+template < >
+inline ext::set < unsigned > FailStateLabel::instance < ext::set < unsigned > > ( ) {
+	return { };
+}
+
 } /* namespace label */
 #endif /* FAIL_STATE_LABEL_H_ */