gh-143145: Fix possible reference leak in ctypes _build_result() (GH-143131)

The result tuple was leaked if __ctypes_from_outparam__() failed for any item.

Signed-off-by: Yongtao Huang <yongtaoh2022@gmail.com>

Author: hyongtao-code

Misc/NEWS.d/next/Library/2025-12-24-14-18-52.gh-issue-143145.eXLw8D.rst

@@ -0,0 +1 @@
+Fixed a possible reference leak in ctypes when constructing results with multiple output parameters on error.

Modules/_ctypes/_ctypes.c

@@ -4557,6 +4557,7 @@ _build_result(PyObject *result, PyObject *callargs,
             v = PyTuple_GET_ITEM(callargs, i);
             v = PyObject_CallMethodNoArgs(v, &_Py_ID(__ctypes_from_outparam__));
             if (v == NULL || numretvals == 1) {
+                Py_XDECREF(tup);
                 Py_DECREF(callargs);
                 return v;
             }