[CVE A/B] CVE-2018-11508 -- compat_get_timex information leak

[Andy Whitcroft]

CVE-2018-11508:
	The compat_get_timex function in kernel/compat.c in the
	Linux kernel before 4.16.9 allows local users to obtain
	sensitive information from kernel memory via adjtimex.

Following this email is a patch for bionic/linux and artful/linux.  This
is a clean cherry-pick in both series.  Earlier series are unaffected by
this issue.

Proposing for SRU to artful and bionic.

-apw