xen to fix various denial of service issues (important)

XEN was updated to fix various denial of service issues. - bnc789945 - CVE-2012-5510: xen: Grant table version switch list corruption vulnerability XSA-26 - bnc789944 - CVE-2012-5511: xen: Several HVM operations do not validate the range of their inputs XSA-27 - bnc789940 - CVE-2012-5512: xen:...