(my_exit): cleanup no attribute noreturn warning.

utilunix.c:360:1: error: function might be candidate for attribute 'noreturn' [-Wsuggest-attribute=noreturn]

Signed-off-by: Andreas Mohr <and@gmx.li>
Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

lib/utilunix.c

@@ -356,8 +356,7 @@ save_stop_handler (void)
  * @param status exit code
  */
 
-void
-my_exit (int status)
+void __attribute__ ((noreturn)) my_exit (int status)
 {
     _exit (status);
 }