doc: original purpose of $sleep is when AC_OUTPUT is not used. * t/ax/test-defs.in (sleep): mention original purpose of $sleep, namely when AC_OUTPUT is not used and hence the sleep done in AC_CONFIG_COMMANDS_* is not done: https://lists.gnu.org/archive/html/bug-automake/2010-10/msg00000.html Discovered by Bruno in his rearch on the "sleep" history: https://lists.gnu.org/archive/html/automake/2024-06/msg00054.html