[Buildroot] [PATCH] package/ntp: bump to version 4.2.8p15

[Peter Korsgaard]

>>>>> "yegorslists" == yegorslists  <yegorslists at googlemail.com> writes:

 > From: Yegor Yefremov <yegorslists at googlemail.com>
 > Signed-off-by: Yegor Yefremov <yegorslists at googlemail.com>

Committed to 2020.02.x and 2020.05.x after updating the commit message
to make it clear that this is a security bump, thanks.

https://support.ntp.org/bin/view/Main/SecurityNotice#June_2020_ntp_4_2_8p15_NTP_Relea

-- 
Bye, Peter Korsgaard