USN-8496-3: cifs-utils vulnerability

USN-8496-1 fixed vulnerabilities in cifs-utils. The update caused a regression and was backed out in USN-8496-2. This update reintroduces the security fix, along with a fix for the regression. Original advisory details: It was discovered that cifs-utils incorrectly dropped root privileges before looking up user information. A local attacker could possibly use this issue to execute arbitrary code as the root user.