GUACAMOLE-217: Merge libavcodec version number update.
GUACAMOLE-217: Merge libavcodec version number update.

mike-jumper/incubator-guacamole-server,mike-jumper/incubator-guacamole-server,glyptodon/guacamole-server,mike-jumper/incubator-guacamole-server,mike-jumper/incubator-guacamole-server,apache/guacamole-server,apache/guacamole-server,apache/guacamole-server,glyptodon/guacamole-server,glyptodon/guacamole-server