VideoBackends: Add Metal renderer

Source/Core/VideoBackends/Metal/MTLPerfQuery.h

@@ -0,0 +1,20 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "VideoCommon/PerfQueryBase.h"
+
+namespace Metal
+{
+class PerfQuery final : public PerfQueryBase
+{
+public:
+  void EnableQuery(PerfQueryGroup type) override {}
+  void DisableQuery(PerfQueryGroup type) override {}
+  void ResetQuery() override {}
+  u32 GetQueryResult(PerfQueryType type) override { return 0; }
+  void FlushResults() override {}
+  bool IsFlushed() const override { return true; }
+};
+}  // namespace Metal