Security update for gnutls (moderate)

This update for gnutls fixes the following issues:

Security issues fixed:

• Improved mitigations against Lucky 13 class of attacks
• CVE-2018-10846: "Just in Time" PRIME + PROBE cache-based side channel
  attack can lead to plaintext recovery (bsc#1105460)
• CVE-2018-10845: HMAC-SHA-384 vulnerable to Lucky thirteen attack due to
  use
  of wrong constant (bsc#1105459)
• CVE-2018-10844: HMAC-SHA-256 vulnerable to Lucky thirteen attack due to
  not enough dummy function calls (bsc#1105437)
• CVE-2017-10790: The _asn1_check_identifier function in Libtasn1 caused a
  NULL pointer dereference and crash (bsc#1047002)

This update was imported from the SUSE:SLE-12-SP3:Update update project.