Excise DL_EXPORT from Include.

Thanks to Skip Montanaro and Kalle Svensson for the patches.
diff --git a/Include/rangeobject.h b/Include/rangeobject.h
index ff6dbc2..b6f571b 100644
--- a/Include/rangeobject.h
+++ b/Include/rangeobject.h
@@ -15,11 +15,11 @@
 they are represented by a start, stop, and step datamembers.
 */
 
-extern DL_IMPORT(PyTypeObject) PyRange_Type;
+PyAPI_DATA(PyTypeObject) PyRange_Type;
 
 #define PyRange_Check(op) ((op)->ob_type == &PyRange_Type)
 
-extern DL_IMPORT(PyObject *) PyRange_New(long, long, long, int);
+PyAPI_FUNC(PyObject *) PyRange_New(long, long, long, int);
 
 #ifdef __cplusplus
 }