[SECURITY] Fedora 17 Update: tinc-1.0.21-1.fc17

tinc is a Virtual Private Network (VPN) daemon that uses tunnelling and encryption to create a secure private network between hosts on the Internet. Because the tunnel appears to the IP level network code as a normal network device, there is no need to adapt any existing software. This tunnelling allows VPN sites to share information with each other over the Internet without exposing any information to others.