Allow to compile the engine without XR support

servers/rendering/rendering_method.h

@@ -34,13 +34,13 @@
 #include "servers/rendering/storage/render_scene_buffers.h"
 #include "servers/rendering_server.h"
 
-#ifdef _3D_DISABLED
+#ifdef XR_DISABLED
 // RendererSceneCull::render_camera is empty when 3D is disabled, but
 // it and RenderingMethod::render_camera have a parameter for XRInterface.
 #define XRInterface RefCounted
-#else // 3D enabled
+#else
 #include "servers/xr/xr_interface.h"
-#endif // _3D_DISABLED
+#endif // XR_DISABLED
 
 class RenderingMethod {
 public: