Added stubs for audio services. (#116)

* stubs for audout:u, audin:u, audrec:u, audren:u, codecctl and decoding tables with nullptr for future implementations

* fixing the changes requested (remove private, explicit)

src/core/hle/service/audio/codecctl.h

@@ -0,0 +1,23 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/hle/service/service.h"
+
+namespace Kernel {
+class HLERequestContext;
+}
+
+namespace Service {
+namespace Audio {
+
+class CodecCtl final : public ServiceFramework<CodecCtl> {
+public:
+    explicit CodecCtl();
+    ~CodecCtl() = default;
+};
+
+} // namespace Audio
+} // namespace Service