gh-83004: Clean up refleak in _pickle initialisation (GH-98841)

(cherry picked from commit d3b82b4)

Co-authored-by: Shantanu <[email protected]>

Author: miss-islington

Misc/NEWS.d/next/Library/2022-11-02-05-53-25.gh-issue-83004.qc_KHr.rst

@@ -0,0 +1 @@
+Clean up refleaks on failed module initialisation in in :mod:`_pickle`

Modules/_pickle.c

@@ -7998,16 +7998,15 @@ PyInit__pickle(void)
     if (st->UnpicklingError == NULL)
         return NULL;
 
-    Py_INCREF(st->PickleError);
-    if (PyModule_AddObject(m, "PickleError", st->PickleError) < 0)
+    if (PyModule_AddObjectRef(m, "PickleError", st->PickleError) < 0) {
         return NULL;
-    Py_INCREF(st->PicklingError);
-    if (PyModule_AddObject(m, "PicklingError", st->PicklingError) < 0)
+    }
+    if (PyModule_AddObjectRef(m, "PicklingError", st->PicklingError) < 0) {
         return NULL;
-    Py_INCREF(st->UnpicklingError);
-    if (PyModule_AddObject(m, "UnpicklingError", st->UnpicklingError) < 0)
+    }
+    if (PyModule_AddObjectRef(m, "UnpicklingError", st->UnpicklingError) < 0) {
         return NULL;
-
+    }
     if (_Pickle_InitState(st) < 0)
         return NULL;