Prepare EffRibInWriter for LLGR_STALE handling
When a peer configured with Long-Lived Graceful Restart goes down,
we need to process all tables which it advertised as LLGR-enabled
and mark all routes as being tagged with LLGR_STALE.
LLGR_STALE community must be added to routes behind import
policy processing since policies can also add this community.
This patch should provide procedures necessary to add LLGR_STALE
community to routes.
JIRA: BGPCEP-495
Change-Id: If921e378f998109b073c628f9913f395496b3139
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
Signed-off-by: Matej Perina <matej.perina@pantheon.tech>