cron: Add path

cron: Add path

Override PATH for /etc/init.d/cron. This is necessary to ensure all programs
can be found when executing the script from remote by using ssh.
(e.g. ssh IP /etc/init.d/cron restart)

Patch from: kentarou matsuyama <matsuyama@thinktube.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@25196 3c298f89-4303-0410-b956-a3cf2f4a3e73