Remove redundant connection_t::status.active field.

The only places where connection_t::status.active is modified is in
ack_h() and terminate_connection(). In both cases, connection_t::edge
is added and removed at the same time, and that's the only places
connection_t::edge is set. Therefore, the following is true at all
times:

    !c->status.active == !c->edge

This commit removes the redundant state information by getting rid of
connection_t::status.active, and using connection_t::edge instead.

src/protocol_auth.c

@@ -805,7 +805,6 @@ bool ack_h(connection_t *c, const char *request) {
 	/* Activate this connection */
 
 	c->allow_request = ALL;
-	c->status.active = true;
 
 	logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Connection with %s (%s) activated", c->name,
 			   c->hostname);