+/* Close standard output. On error, issue a diagnostic and _exit
+ with status 'exit_failure'.
+
+ Also close standard error. On error, _exit with status 'exit_failure'.
+
+ Since close_stdout is commonly registered via 'atexit', POSIX
+ and the C standard both say that it should not call 'exit',
+ because the behavior is undefined if 'exit' is called more than
+ once. So it calls '_exit' instead of 'exit'. If close_stdout
+ is registered via atexit before other functions are registered,
+ the other functions can act before this _exit is invoked.
+
+ Applications that use close_stdout should flush any streams
+ other than stdout and stderr before exiting, since the call to
+ _exit will bypass other buffer flushing. Applications should
+ be flushing and closing other streams anyway, to check for I/O
+ errors. Also, applications should not use tmpfile, since _exit
+ can bypass the removal of these files.
+
+ It's important to detect such failures and exit nonzero because many
+ tools (most notably `make' and other build-management systems) depend
+ on being able to detect failure in other tools via their exit status. */
+