dirstate-item: Make constructor parameters optional

… in the C implementation of DirstateItem, like they already were in the
Python and Rust ones.

Differential Revision: https://phab.mercurial-scm.org/D11521

mercurial/cext/parsers.c

@@ -71,7 +71,7 b' static PyObject *dirstate_item_new(PyTyp'
 	clean_p2 = 0;
 	possibly_dirty = 0;
 	parentfiledata = Py_None;
-	if (!PyArg_ParseTupleAndKeywords(args, kwds, "iiiiiiiO", keywords_name,
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|iiiiiiiO", keywords_name,
 	                                 &wc_tracked, &p1_tracked, &p2_tracked,
 	                                 &merged, &clean_p1, &clean_p2,
 	                                 &possibly_dirty, &parentfiledata