rsx: Workaround for exit deadlock

- Avoids games locking up when the stop button is pressed

rpcs3/Emu/RSX/RSXThread.cpp

@@ -606,6 +606,13 @@ namespace rsx
 
 	void thread::on_exit()
 	{
+		// Deregister violation handler
+		g_access_violation_handler = nullptr;
+
+		// Clear any pending flush requests to release threads
+		std::this_thread::sleep_for(10ms);
+		do_local_task(rsx::FIFO_state::lock_wait);
+
 		m_rsx_thread_exiting = true;
 		g_dma_manager.join();
 	}

rpcs3/Emu/RSX/VK/VKGSRender.cpp

@@ -545,6 +545,9 @@ VKGSRender::~VKGSRender()
 	//Wait for device to finish up with resources
 	vkDeviceWaitIdle(*m_device);
 
+	// Clear flush requests
+	m_flush_requests.clear_pending_flag();
+
 	//Texture cache
 	m_texture_cache.destroy();