Upgrade NTP to 4.2.8p4.

Security: FreeBSD-SA-15:25.ntp
Security: CVE-2015-7871
Security: CVE-2015-7855
Security: CVE-2015-7854
Security: CVE-2015-7853
Security: CVE-2015-7852
Security: CVE-2015-7851
Security: CVE-2015-7850
Security: CVE-2015-7849
Security: CVE-2015-7848
Security: CVE-2015-7701
Security: CVE-2015-7703
Security: CVE-2015-7704, CVE-2015-7705
Security: CVE-2015-7691, CVE-2015-7692, CVE-2015-7702
Approved by: so

Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

This commit was generated by cvs2svn to compensate for changes in r54359,
which included commits to RCS files with non-trunk default branches.

Virgin import of ntpd 4.0.98f