Simplify and speedup uses of Py_BuildValue():

* Py_BuildValue("(OOO)",a,b,c)  -->  PyTuple_Pack(3,a,b,c)
* Py_BuildValue("()",a)         -->  PyTuple_New(0)
* Py_BuildValue("O", a)         -->  Py_INCREF(a)
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index d7c9da5..6f90fb9 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -1227,7 +1227,7 @@
 		if (reader == NULL)
 			return NULL;
 		if (n <= 0)
-			args = Py_BuildValue("()");
+			args = PyTuple_New(0);
 		else
 			args = Py_BuildValue("(i)", n);
 		if (args == NULL) {
@@ -2104,7 +2104,7 @@
 		Py_DECREF(writer);
 		return -1;
 	}
-	args = Py_BuildValue("(O)", value);
+	args = PyTuple_Pack(1, value);
 	if (args == NULL) {
 		Py_DECREF(value);
 		Py_DECREF(writer);