buildroot

quagga: add upstream security fix for CVE-2017-16227

>From the advisory:
http://www.openwall.com/lists/oss-security/2017/10/30/4

It was discovered that the bgpd daemon in the Quagga routing suite does
not properly calculate the length of multi-segment AS_PATH UPDATE
messages, causing bgpd to drop a session and potentially resulting in
loss of network connectivity.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>