Changelog:
=============
* anacron: Add support for NO_MAIL_OUTPUT environment variable
* anacron: Support enabling anacron jobs on battery power
* crond: Support -n crontab entry option to disable mailing the output
* crontab: Make a backup of the crontab file on edition and deletion
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>