USN-5078-2: Squashfs-Tools vulnerabilities

USN-5078-1 fixed several vulnerabilities in Squashfs-Tools. This update provides the corresponding update for Ubuntu 16.04 ESM. Original advisory details: Etienne Stalmans discovered that Squashfs-Tools mishandled certain malformed SQUASHFS files. An attacker could use this vulnerability to write arbitrary files to the filesystem. (CVE-2021-40153) Richard Weinberger discovered that Squashfs-Tools mishandled certain malformed SQUASHFS files. An attacker could use this vulnerability to write arbitrary files to the filesystem. (CVE-2021-41072)