Issue #28915: Exclude _Py_VaBuildStack from the limited API.

Include/modsupport.h

@@ -21,7 +21,9 @@ extern "C" {
 #endif /* !Py_LIMITED_API */
 #define Py_BuildValue                   _Py_BuildValue_SizeT
 #define Py_VaBuildValue                 _Py_VaBuildValue_SizeT
+#ifndef Py_LIMITED_API
 #define _Py_VaBuildStack                _Py_VaBuildStack_SizeT
+#endif
 #else
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(PyObject *) _Py_VaBuildValue_SizeT(const char *, va_list);
@@ -54,12 +56,14 @@ PyAPI_FUNC(int) PyArg_VaParseTupleAndKeywords(PyObject *, PyObject *,
                                                   const char *, char **, va_list);
 #endif
 PyAPI_FUNC(PyObject *) Py_VaBuildValue(const char *, va_list);
+#ifndef Py_LIMITED_API
 PyAPI_FUNC(PyObject **) _Py_VaBuildStack(
     PyObject **small_stack,
     Py_ssize_t small_stack_len,
     const char *format,
     va_list va,
     Py_ssize_t *p_nargs);
+#endif
 
 #ifndef Py_LIMITED_API
 typedef struct _PyArg_Parser {