Security update for libvirt (moderate)

This update for libvirt fixes the following issues: Security issue fixed: - CVE-2018-3639: Add support for 'ssbd' and 'virt-ssbd' CPUID feature bits to address V4 Speculative Store Bypass aka "Memory Disambiguation" bsc1092885. Bug fixes: - bsc1094325: Enable virsh blockresize for XEN guests...