tmf: Fix the actual end time of state system modules

tmf: Fix the actual end time of state system modules

State providers keep track of the latest event that was handled is returns
this time as the current end time.

State system analysis module use this time to determine if an analysis is ready
to be queried. Also on the way to fix bug 488757.

Change-Id: I58308da05c3105f0a528398622658c3fb3f2250f
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/69760
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>