Excise DL_EXPORT from Include.

Thanks to Skip Montanaro and Kalle Svensson for the patches.
diff --git a/Include/symtable.h b/Include/symtable.h
index 8bfe9aa..9bf2a2a 100644
--- a/Include/symtable.h
+++ b/Include/symtable.h
@@ -50,15 +50,15 @@
 	struct symtable *ste_table;
 } PySymtableEntryObject;
 
-extern DL_IMPORT(PyTypeObject) PySymtableEntry_Type;
+PyAPI_DATA(PyTypeObject) PySymtableEntry_Type;
 
 #define PySymtableEntry_Check(op) ((op)->ob_type == &PySymtableEntry_Type)
 
-extern DL_IMPORT(PyObject *) PySymtableEntry_New(struct symtable *,
+PyAPI_FUNC(PyObject *) PySymtableEntry_New(struct symtable *,
 						 char *, int, int);
 
-DL_IMPORT(struct symtable *) PyNode_CompileSymtable(struct _node *, char *);
-DL_IMPORT(void) PySymtable_Free(struct symtable *);
+PyAPI_FUNC(struct symtable *) PyNode_CompileSymtable(struct _node *, char *);
+PyAPI_FUNC(void) PySymtable_Free(struct symtable *);
 
 
 #define TOP "global"