package/mrouted: add sysv init script

package/mrouted: add sysv init script

The upstream mrouted package comes with its own systemd unit file, but
no SysV init script.  This script is a modified copy of the sysklogd
init script, but set to start after networking.

Note: for mrouted to start it requires at least two MULTICAST capable
      interfaces that are UP.  This is why an added startup delay of 30
      seconds (-w 30) was added, in case the system has DHCP enabled.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>