Check if CPU time tracking is expected to work

This check will allow statsd to decide whether it should add a puller
for total CPU time tracking. Reading total CPU time on devices that does
not support CPU time tracking is wasteful, passing all zero times around
and recording "no data" state.

Bug: 174245730
Test: atest libtimeinstate_test
Test: cmd stats pull-source 10095
Change-Id: Ib6155af4cbd6c639d356118934237d7dfd76b3a8