Updated libxml2 packages fix security vulnerability

When running in recovery mode, certain invalid XML documents would trigger an infinite recursion in libxml2 that ran until all stack space was exhausted. This vulnerability could have been used to facilitate a denial-of-sevice attack (CVE-2016-3627). libxml2 limits the number of recursions an XML document can contain so to protect against the “Billion Laughs” denial-of-service attack. Unfortunately, the underlying counter was not incremented properly in all necessary locations. Therefore, specially crafted XML documents could exhaust all available stack space and crash the XML parser without running into the recursion limit (CVE-2016-3705).