tmf: Bug 494197: Empty event list for CallStackEntry when no process

The three-level deep loop to populate the event list from the build
thread did not reach the third level if a trace did not have processes
or threads. The loops are replaced with a recursive consumer.

Change-Id: Ie7eebb57f562bad0c6620ae08fcde8b585c52ca9
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/72916
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>