hle: service: Stub OLSC Initialize and SetSaveDataBackupSettingEnabled functions.

- Used by Animal Cross: New Horizons v1.6.0 update, minimal stub gets this update working.

src/core/hle/service/olsc/olsc.h

@@ -0,0 +1,16 @@
+// Copyright 2020 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+namespace Service::SM {
+class ServiceManager;
+}
+
+namespace Service::OLSC {
+
+/// Registers all SSL services with the specified service manager.
+void InstallInterfaces(SM::ServiceManager& service_manager);
+
+} // namespace Service::OLSC