Update leap-seconds to leap-seconds.3661459200.
NO leap second will be introduced at the end of June 2016.

This commit reapplies the r298887 minor spelling fix.

Obtained from: ftp://tycho.usno.navy.mil/pub/ntp/.
See also: http://www.iers.org/SharedDocs/News/EN/BulletinC.html
MFC after: 2 weeks