ntp: security bump to version 4.2.8p11

ntp: security bump to version 4.2.8p11

Fixed or improved security issues:

  CVE-2016-1549 (fixed in 4.2.8p7; this release adds protection): A
  malicious authenticated peer can create arbitrarily-many ephemeral
  associations in order to win the clock selection algorithm

  CVE-2018-7182: Buffer read overrun leads to undefined behavior and
  information leak

  CVE-2018-7170: Multiple authenticated ephemeral associations

  CVE-2018-7184: Interleaved symmetric mode cannot recover from bad
  state

  CVE-2018-7185: Unauthenticated packet can reset authenticated
  interleaved association

  CVE-2018-7183: ntpq:decodearr() can write beyond its buffer limit

Drop patch #3. libntpq_a_CFLAGS now includes NTP_HARD_CFLAGS via
AM_CFLAGS.

Add license file hash.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>