Security update for util-linux (important)

This update for util-linux fixes the following issues:

This security issue was fixed:

• CVE-2017-2616: In su with PAM support it was possible for local users to
  send SIGKILL to selected other processes with root privileges
  (bsc#1023041).

This non-security issues were fixed:

• lscpu: Implement WSL detection and work around crash (bsc#1019332)
• fstrim: De-duplicate btrfs sub-volumes for "fstrim -a" and bind mounts
  (bsc#1020077)
• Fix regressions in safe loop re-use patch set for libmount (bsc#1012504)
• Disable ro checks for mtab (bsc#1012632)
• Ensure that the option "users,exec,dev,suid" work as expected on NFS
  mounts (bsc#1008965)
• Fix empty slave detection to prevent 100% CPU load in some cases
  (bsc#1020985)

This update was imported from the SUSE:SLE-12-SP2:Update update project.