MFC r311103, r311907:

MFC r311103, r311907:

  Update ntp.conf to use the ntpd pool feature.

  Our previous ntp.conf file configured 3 servers from freebsd.pool.ntp.org
  using 3 separate 'server' config lines.  That is now replaced with a single
  'pool' line which causes ntpd to add multiple servers from the pool.

  More than just making the config smaller, the pool feature in ntpd has one
  major advantage over configuring 3 separate servers from a pool: if a server
  that was added using a 'pool' statement provides bad time (initially or at
  some later date), ntpd automatically discards it and configures a new
  different server from the pool without needing to be restarted.

  These changes also add a 'tos' line to control how many pool servers get
  added, a 'restrict source' line that is required to allow ntpd to add new
  peers from the pool, and it deletes a 'restrict 127.127.1.0' line that does
  nothing and should never have been there (127.127.1.0 is not a valid IP
  address, it's a refclock identifier).

  Add "pool" to the keywords that rc.d/ntpdate examines to
  find a server address in ntp.conf.