Add missing copyright in SampleDecoder.cpp (#7030)

src/core/SampleDecoder.cpp

@@ -1,3 +1,27 @@
+/*
+ * SampleDecoder.cpp - Decodes audio files in various formats
+ *
+ * Copyright (c) 2023 saker <sakertooth@gmail.com>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
 #include "SampleDecoder.h"
 
 #include <QFile>