Security Update: ntp

After the last call, Pat only accept bug fixes and security fixes updates in the last batch of update :

• ntp: Upgraded to 4.2.8p8 for all Slackware releases back to 13.0
• imagemagick: Upgraded to 6.9.4_7
• xfce4-panel: Rebuilt to fix blinking issue
• lxc: Rebuilt to fix shutdown issue
• libxml2: Rebuilt to fix attribute decoding issue
• net-snmp: Rebuilt to include ucd-snmp/diskio module