messages not related to an account.
* lib/prototypes.h, libmisc/cleanup.c, libmisc/cleanup_group.c,
libmisc/cleanup_user.c, libmisc/Makefile.am: Added stack of
cleanup functions to be executed on exit.
* NEWS, src/groupadd.c, src/groupdel.c, src/groupmod.c: Only
report success to audit and syslog when the changes are committed
to the system. Do not log failure for on-memory changes to audit
or syslog. Make sure failures and inconsistencies will be reported
in case of unexpected failures (e.g. malloc failures). Only
specify an audit message if it is not implicitly implied by the
type argument. Removed fail_exit (replaced by atexit(do_cleanups)).
