Core: Move CountPerformanceMarker to VideoInterface to eliminate a Throttle call. PerformanceMetrics: Fixes/Cleanups.

Source/Core/Core/HW/VideoInterface.cpp

@@ -914,6 +914,10 @@ void VideoInterfaceManager::Update(u64 ticks)
   {
     // Throttle before SI poll so user input is taken just before needed. (lower input latency)
     core_timing.Throttle(ticks);
+
+    // This is a nice place to measure performance so we don't have to Throttle elsewhere.
+    g_perf_metrics.CountPerformanceMarker(ticks, m_system.GetSystemTimers().GetTicksPerSecond());
+
     Core::UpdateInputGate(!Config::Get(Config::MAIN_INPUT_BACKGROUND_INPUT),
                           Config::Get(Config::MAIN_LOCK_CURSOR));
     auto& si = m_system.GetSerialInterface();