SaveData: Implemented the SystemSaveData archive.

It will be stored in the /syssavedata folder. This archive is user by various Services and possibly games via the FS:U service.

src/core/file_sys/archive_systemsavedata.h

@@ -0,0 +1,31 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+
+#include "core/file_sys/disk_archive.h"
+#include "core/loader/loader.h"
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// FileSys namespace
+
+namespace FileSys {
+
+/// File system interface to the SaveData archive
+class Archive_SystemSaveData final : public DiskArchive {
+public:
+    Archive_SystemSaveData(const std::string& mount_point);
+
+    /**
+     * Initialize the archive.
+     * @return true if it initialized successfully
+     */
+    bool Initialize();
+
+    std::string GetName() const override { return "SystemSaveData"; }
+};
+
+} // namespace FileSys