Fix integer overflow when replacing certificates in cache (CVE-2021-41991)

Fix integer overflow in gmp plugin which can lead to denial of service
(CVE-2021-41990)

Update to upstream version '5.7.1'
with Debian dir 72f82c6dc54a03e0a4ef30d019024a741edf8eb4

closes: #814927

Apparmor cosmetic fixes

See merge request debian/strongswan!2

Update to upstream version '5.7.0'
with Debian dir b608300a1e1f88db62d14d08a55ca09f3603f054