[SECURITY] gnutls (CVE-2015-6251)

[Yaakov Selkowitz]

Dr. Volker,

http://www.gnutls.org/security.html#GNUTLS-SA-2015-3

Fix: upgrade to 3.3.17, which is supposed to be ABI-compatible with 3.2
(minus the removal of the libgnutls-xssl wrapper library, which is
unused AFAIK), OR add the following patch to 3.2.20:

https://gitlab.com/gnutls/gnutls/commit/272854367efc130fbd4f1a51840d80c630214e12.diff

TIA,

Yaakov