Modify algorithmic operations with timespec

:Release Notes:
Modify algorithmic operations with timespec
Modify unit tests

:Detailed Notes:
A test "test_clock" depended on overflow result of numeric operations

:Testing Performed:
Unit tests on different platforms

:QA Notes:

:Issues Addressed:
[ANG-482] luna-service2 test suite : test_clock failed

Open-webOS-DCO-1.0-Signed-off-by: Alekseyev Oleksandr<alekseyev.oleksandr@lge.com>

Change-Id: Ifaf6b4b085a175db1e75402e7a325d874f1dd1b1
Reviewed-on: https://g2g.palm.com/4551
Reviewed-by: DCO Verification
Reviewed-by: Alekseyev Oleksandr <alekseyev.oleksandr@lge.com>
Tested-by: Alekseyev Oleksandr <alekseyev.oleksandr@lge.com>
Reviewed-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>