gossipd: increase number of gossiping peers.

We only chose 3 peers to gossip with us (down from 8 last release).
There's no justification for this number, or reason to believe that
it is sufficient to keep us in sync.

Be more conservative for now; we can always decrease it later once
we have more data.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

gossipd/seeker.c

@@ -77,7 +77,7 @@ struct seeker {
 	bool unknown_nodes;
 
 	/* Peers we've asked to stream us gossip */
-	struct peer *gossiper_softref[3];
+	struct peer *gossiper_softref[5];
 
 	/* A peer that told us about unknown gossip. */
 	struct peer *preferred_peer_softref;