tmf: Tweaks to CallStackStateProvider

tmf: Tweaks to CallStackStateProvider

- Add a considerEvent() method to put all checks in. This avoids
  running checks more than once per event.
- Make the abstract methods protected instead, they should not be called
  by external components.
- Add a check when popping state values if func_exit names are available.
  This makes sure the value matches the current function we are in. If it
  doesn't, log a warning in the error log. This will most definitely happen
  if there are lost events in the trace.

Change-Id: I1f2014486768c9317cbddb9556faf3e061f130b0
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/16393
Tested-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
IP-Clean: Patrick Tasse <patrick.tasse@gmail.com>