Core: Avoid (Some) Global System Accessor

Source/Core/DolphinNoGUI/PlatformHeadless.cpp

@@ -3,7 +3,9 @@
 
 #include <cstdio>
 #include <thread>
+
 #include "Core/Core.h"
+#include "Core/System.h"
 #include "DolphinNoGUI/Platform.h"
 
 namespace
@@ -27,7 +29,7 @@ void PlatformHeadless::MainLoop()
   while (m_running.IsSet())
   {
     UpdateRunningFlag();
-    Core::HostDispatchJobs();
+    Core::HostDispatchJobs(Core::System::GetInstance());
     std::this_thread::sleep_for(std::chrono::milliseconds(100));
   }
 }