Author: Andrew Nicols
MDL-62326 core_antivirus: Implement null provider
http://git.moodle.org/gw?p=moodle.git;a=commit;h=aad32d11f595a3d7db6a19b147a23cfb53c0e194
http://github.com/moodle/moodle/commit/aad32d11f595a3d7db6a19b147a23cfb53c0e194
+ 3.5 en [privacy:metadata,core_antivirus]