d3d: Add D3DDEVTYPE_NULLREF definition.
diff --git a/include/d3d9types.h b/include/d3d9types.h
index 3c4b8a1..fc8b40d 100644
--- a/include/d3d9types.h
+++ b/include/d3d9types.h
@@ -740,6 +740,7 @@
     D3DDEVTYPE_HAL         = 1,
     D3DDEVTYPE_REF         = 2,
     D3DDEVTYPE_SW          = 3,
+    D3DDEVTYPE_NULLREF     = 4,
 
     D3DDEVTYPE_FORCE_DWORD = 0xffffffff
 } D3DDEVTYPE;