bpo-37483: add _PyObject_CallOneArg() function (#14558)

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index a0eb505..4b98578 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1340,8 +1340,7 @@
         return NULL;
     }
 
-    PyObject *args[1] = {obj};
-    return _PyObject_FastCall(gs->prop_get, args, 1);
+    return _PyObject_CallOneArg(gs->prop_get, obj);
 }
 
 static int
@@ -1362,7 +1361,7 @@
         return -1;
     }
     if (value == NULL)
-        res = PyObject_CallFunctionObjArgs(func, obj, NULL);
+        res = _PyObject_CallOneArg(func, obj);
     else
         res = PyObject_CallFunctionObjArgs(func, obj, value, NULL);
     if (res == NULL)