ntp security and bug fix update

[4.2.6p5-25.0.1]

• add disable monitor to default ntp.conf [CVE-2013-5211]
  [4.2.6p5-25]
• don’t allow spoofed packet to enable symmetric interleaved mode
  (CVE-2016-1548)
• check mode of new source in config command (CVE-2016-2518)
• make MAC check resilient against timing attack (CVE-2016-1550)
  [4.2.6p5-24]
• fix crash with invalid logconfig command (CVE-2015-5194)
• fix crash when referencing disabled statistic type (CVE-2015-5195)
• don’t hang in sntp with crafted reply (CVE-2015-5219)
• don’t crash with crafted autokey packet (CVE-2015-7691, CVE-2015-7692,
  CVE-2015-7702)
• fix memory leak with autokey (CVE-2015-7701)
• don’t allow setting driftfile and pidfile remotely (CVE-2015-7703)
• don’t crash in ntpq with crafted packet (CVE-2015-7852)
• check key ID in packets authenticated with symmetric key (CVE-2015-7974)
• fix crash with reslist command (CVE-2015-7977, CVE-2015-7978)
• don’t allow spoofed packets to demobilize associations (CVE-2015-7979,
  CVE-2016-1547)
• don’t accept server/peer packets with zero origin timestamp (CVE-2015-8138)
• fix infinite loop in ntpq/ntpdc (CVE-2015-8158)
• fix resetting of leap status (#1242553)
• extend rawstats log (#1242877)
• report clock state changes related to leap seconds (#1242935)
• allow -4/-6 on restrict lines with mask (#1304492)
• explain synchronised state in ntpstat man page (#1309594)