feat(Windows64): safely exit game & get monitors size that has the game window instead of primary

Minecraft.Client/Windows64/Windows64_Minecraft.h

@@ -1,4 +1,12 @@
 #pragma once
 
+#include <d3d11.h>
+
+extern BOOL g_bWidescreen;
+
 extern int g_iScreenWidth;
-extern int g_iScreenHeight;
+extern int g_iScreenHeight;
+
+extern ID3D11Device* g_pd3dDevice;
+
+void CleanupDevice();