[Enhancement] [RHEL/6] Add audit remediations for *time* group based system calls (adjtimex, settimeofday & stime)

This PR adds RHEL-6 audit remediations for the following three time group based system calls:
* adjtimex,
* settimeofday, and
* stime.

The case of clock_settime system call has been intentionally left out, since it will need special care (slightly different remediation script).

Testing report:
-------------------
The proposed change has been tested on RHEL-6 (on both 32-bit & 64-bit archs) & works as expected (on each of them).

Please review.

Thanks, Jan.