Import Ubuntu changes 3.4.10-4ubuntu1.8

gnutls28 (3.4.10-4ubuntu1.8) xenial; urgency=medium

  * d/p/50_Update-session_ticket.c-to-add-support-for-zero-leng.patch:
    - add support for zero length  session tickets returned from the server,
      thanks Rod for the backport and testing! (lp: #1876286)