igmpproxy: Multiple downlink interfaces fix.

igmpproxy: Multiple downlink interfaces fix.

from Erik Tews <erik@datenzone.de>

This patch has two effects. First, the quickleave feature/behaviour is
disabled for all groups that are used on more than one interface. The
idea of quickleave is to leave a group fast and later figure out whether
there is still somebody interested in that group. For groups used on
more than one interface, it is already known that there is still
somebody interested in that group.

Second, when a leave is received for a group that is used on more than
one interface, igmpproxy sends queries on all interface to discover
remeining listeners for that group. Previously these queries were only
send on the interface the leave was received on, so that listeners on
the other interfaces were not discovered and the group might be left on
the upstream router incorrectly.

This patch can be improved by sending the queries only on the interface
the leave was received on and adapting the algorithm in
internAgeRoute(...) in rttable.c in a way that only one interface is
actually processed and all other interfaces of the route are silently
assumed to be still active.

Signed-off-by: Erik Tews <erik@datenzone.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44859 3c298f89-4303-0410-b956-a3cf2f4a3e73