Security update for ovmf

Open Source Vulnerabilities SUSE-SU-2018:4207-1

This update for ovmf fixes the following issues: Security issues fixed: - CVE-2018-3613: Fixed AuthVariable Timestamp zeroing issue on APPEND_WRITE (bsc#1115916). - CVE-2017-5731: Fixed privilege escalation via processing of malformed files in TianoCompress.c (bsc#1115917). - CVE-2017-5732: Fixed privilege escalation via processing of malformed files in BaseUefiDecompressLib.c (bsc#1115917). - CVE-2017-5733: Fixed privilege escalation via heap-based buffer overflow in MakeTable() function (bsc#1115917). - CVE-2017-5734: Fixed privilege escalation via stack-based buffer overflow in MakeTable() function (bsc#1115917). - CVE-2017-5735: Fixed privilege escalation via heap-based buffer overflow in Decode() function (bsc#1115917).