bootmanager: Forward declare System and SystemResultStatus

src/yuzu/bootmanager.h

@@ -16,7 +16,6 @@
 #include <QWindow>
 
 #include "common/thread.h"
-#include "core/core.h"
 #include "core/frontend/emu_window.h"
 
 class GRenderWindow;
@@ -24,6 +23,11 @@ class GMainWindow;
 class QKeyEvent;
 class QStringList;
 
+namespace Core {
+enum class SystemResultStatus : u32;
+class System;
+} // namespace Core
+
 namespace InputCommon {
 class InputSubsystem;
 }