bpo-40479: Fix undefined behavior in Modules/_hashopenssl.c (GH-31153)

va_end() must be called before returning.
(cherry picked from commit 59e004a)

Co-authored-by: Zackery Spytz <[email protected]>

Author: miss-islington

Misc/NEWS.d/next/Core and Builtins/2022-02-06-23-08-30.bpo-40479.zED3Zu.rst

@@ -0,0 +1 @@
+Add a missing call to ``va_end()`` in ``Modules/_hashopenssl.c``.

Modules/_hashopenssl.c

@@ -311,6 +311,7 @@ _setException(PyObject *exc, const char* altmsg, ...)
         } else {
             PyErr_FormatV(exc, altmsg, vargs);
         }
+        va_end(vargs);
         return NULL;
     }
     va_end(vargs);