[SRU T, U, V, W] sysctl to disable unprivileged user namespace unsharing

[Kamal Mostafa]

On Thu, Jun 23, 2016 at 11:53:56AM -0700, Kamal Mostafa wrote:
> From: Kamal Mostafa <kamal at canonical.com>
> 
> Mitigation of unprivileged user namespaces vulnerability.
> 
> BugLink: https://bugs.launchpad.net/bugs/1595350

This additional bug reference to be added:

BugLink: https://bugs.launchpad.net/bugs/1555338