ntp: Update to 4.2.8p11

ntp: Update to 4.2.8p11

For details see:
http://support.ntp.org/bin/view/Main/SecurityNotice#Recent_Vulnerabilities

"This release addresses five security issues in ntpd:

	LOW/MEDIUM: Sec 3012 / CVE-2016-1549 / VU#961909: Sybil vulnerability: ephemeral
	association attack
		While fixed in ntp-4.2.8p7, there are significant additional protections for
		this issue in 4.2.8p11.
		Reported by Matt Van Gundy of Cisco.
	INFO/MEDIUM: Sec 3412 / CVE-2018-7182 / VU#961909: ctl_getitem(): buffer read overrun
	leads to undefined behavior and information leak
		Reported by Yihan Lian of Qihoo 360.
	LOW: Sec 3415 / CVE-2018-7170 / VU#961909: Multiple authenticated ephemeral associations
		Reported on the questions@ list.
	LOW: Sec 3453 / CVE-2018-7184 / VU#961909: Interleaved symmetric mode cannot recover
	from bad state
		Reported by Miroslav Lichvar of Red Hat.
	LOW/MEDIUM: Sec 3454 / CVE-2018-7185 / VU#961909: Unauthenticated packet can reset
	authenticated interleaved association
		Reported by Miroslav Lichvar of Red Hat.

one security issue in ntpq:

	MEDIUM: Sec 3414 / CVE-2018-7183 / VU#961909: ntpq:decodearr() can write beyond its
	buffer limit
		Reported by Michael Macnair of Thales-esecurity.com.

and provides over 33 bugfixes and 32 other improvements."

Best,
Matthias

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>