busybox: preserve crontabs

busybox: preserve crontabs

/etc/syslog.conf is used by sysklogd, and /etc/crontabs is used
by crond, both features of busybox.  Given this, ownership for
these files should be bound to busybox, especially if one day
there's a way to do an in-place opkg update of busybox.

There's also the busybox provided syslogd which uses this file
if CONFIG_BUSYBOX_FEATURE_SYSLOGD_CFG is set.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>