9553 C11 functions quick_exit and at_quick_exit should be visible in C++11.

@@ -56,13 +56,16 @@
 #endif  /* __STDC_VERSION__ - 0 >= 201112L */
 #endif  /* !defined(_NORETURN_KYWD) */
 
 #if !defined(_STRICT_SYMBOLS) || defined(_STDC_C11)
 extern void *aligned_alloc(size_t, size_t);
+#endif /* !_STRICT_SYMBOLS || _STDC_C11 */
+
+#if !defined(_STRICT_SYMBOLS) || defined(_STDC_C11) || __cplusplus >= 201103L
 extern int at_quick_exit(void (*)(void));
 extern _NORETURN_KYWD void quick_exit(int);
-#endif /* !_STRICT_SYMBOLS || _STDC_C11 */
+#endif /* !_STRICT_SYMBOLS || _STDC_C11 || __cplusplus >= 201103L */
 
 #if __cplusplus >= 199711L
 }
 #endif