replication: Make --disable-replication compile again

Broken in commit daa33c52.

Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Message-id: 1493298053-17140-1-git-send-email-armbru@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>