Don't discard ConfigChanged callback handle

Source/Core/VideoCommon/AbstractGfx.cpp

@@ -18,7 +18,8 @@ std::unique_ptr<AbstractGfx> g_gfx;
 
 AbstractGfx::AbstractGfx()
 {
-  ConfigChangedEvent::Register([this](u32 bits) { OnConfigChanged(bits); }, "AbstractGfx");
+  m_config_changed =
+      ConfigChangedEvent::Register([this](u32 bits) { OnConfigChanged(bits); }, "AbstractGfx");
 }
 
 bool AbstractGfx::IsHeadless() const

Source/Core/VideoCommon/AbstractGfx.h

@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include "Common/HookableEvent.h"
 #include "Common/MathUtil.h"
 
 #include "VideoCommon/RenderState.h"
@@ -166,6 +167,9 @@ public:
 protected:
   AbstractFramebuffer* m_current_framebuffer = nullptr;
   const AbstractPipeline* m_current_pipeline = nullptr;
+
+private:
+  Common::EventHook m_config_changed;
 };
 
 extern std::unique_ptr<AbstractGfx> g_gfx;