Updated libxml2 packages fix security vulnerability

A heap-based buffer overflow flaw was found in the way libxml2 parsed certain crafted XML input. A remote attacker could provide a specially crafted XML file that, when opened in an application linked against libxml2, would cause the application to crash or execute arbitrary code with the permissions of the user running the application (CVE-2016-1834, CVE-2016-1840). Multiple denial of service flaws were found in libxml2. A remote attacker could provide a specially crafted XML file that, when processed by an application using libxml2, could cause that application to crash (CVE-2016-1762, CVE-2016-1833, CVE-2016-1835, CVE-2016-1836, CVE-2016-1837, CVE-2016-1838, CVE-2016-1839, CVE-2015-8806, CVE-2016-2073, CVE-2016-4483, CVE-2016-4447, CVE-2016-4448, CVE-2016-4449). The libxml2 package has been updated to version 2.9.4, fixing these issues and other bugs.