tmf: Make TmfTrace.buildStateSystem() return an IStatus

tmf: Make TmfTrace.buildStateSystem() return an IStatus

This removes the need for the SuppressWarnings("unused"), since
every implementation can now return an IStatus (or simply a
Status.OK_STATUS if everything went fine) instead of throwing
an exception.

Change-Id: I23f644988420bbfb4a26caf5e0099c4e26e37072
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/14630
Tested-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
IP-Clean: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>