strongswan: security bump to version 5.3.4

Fixes:
CVE-2015-8023 - authentication bypass vulnerability in the eap-mschapv2
plugin that was caused by insufficient verification of the internal
state when handling EAP-MSCHAPv2 Success messages received by the
client.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>