Remove nonsense msxml IDL attributes.

diff --git a/include/msxml.idl b/include/msxml.idl
index 5f20f98..68d6bdc 100644
--- a/include/msxml.idl
+++ b/include/msxml.idl
@@ -201,8 +201,8 @@
     [id(DISPID_XMLELEMENT_ADDCHILD)]
     HRESULT addChild(
         [in] IXMLElement2 *pChildElem,
-        [retval, out] long lIndex,
-        [retval, out] long lReserved);
+        [in] long lIndex,
+        [in] long lReserved);
 
     [id(DISPID_XMLELEMENT_REMOVECHILD)]
     HRESULT removeChild([in]IXMLElement2 *pChildElem);