openssh: Whitelist CVE-2016-20012

Whitelist CVE-2016-20012 as the upstream OpenSSH developers
see this as an important security feature and do not intend to
'fix' it.
Link: https://security-tracker.debian.org/tracker/CVE-2016-20012
https://ubuntu.com/security/CVE-2016-20012



Signed-off-by: Sana Kazi <Sana.Kazi@kpit.com>
Signed-off-by: Sana Kazi <sanakazisk19@gmail.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>