gnutls: Upgraded to version 3.2.13

gnutls 2.12.23 contains GPLv3 sources for libgnutls. To fix
this issue gnutls was upgraded to version 3.2.13.
The recipes were backpoted from the upstream.

Signed-off-by: Mikhail Durnev <mikhail_durnev@mentor.com>
gnutls: Fixed packaging

Added package gnutls-xssl to eliminate warnings produced by debian_package_name_hook()

Signed-off-by: Mikhail Durnev <mikhail_durnev@mentor.com>