common: Rework timekeeping with native RDTSC and port to linux

src/common/native_clock.h

@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <chrono>
+#include "common/types.h"
+
+namespace Common {
+
+class NativeClock final {
+public:
+    explicit NativeClock();
+
+    u64 GetTscFrequency() const {
+        return rdtsc_frequency;
+    }
+
+    u64 GetTimeNS() const;
+    u64 GetTimeUS() const;
+    u64 GetTimeMS() const;
+    u64 GetUptime() const;
+    u64 GetProcessTimeUS() const;
+
+private:
+    u64 rdtsc_frequency;
+    u64 ns_rdtsc_factor;
+    u64 us_rdtsc_factor;
+    u64 ms_rdtsc_factor;
+};
+
+} // namespace Common