USN-4737-2: Bind vulnerability

USN-4737-1 fixed a vulnerability in Bind. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM. Original advisory details: It was discovered that Bind incorrectly handled GSSAPI security policy negotiation. A remote attacker could use this issue to cause Bind to crash, resulting in a denial of service, or possibly execute arbitrary code. In the default installation, attackers would be isolated by the Bind AppArmor profile.