ctf: Plug the unsigned utils comparator into Stream comparator.

ctf: Plug the unsigned utils comparator into Stream comparator.

This patch-set fixes a pending TODO found randomly.
It modifies the code to use the unsigned comparator and avoid
bugs for large timestamp values.

The comparator no longer accept null values.

Change-Id: Idee0e56edfe85ba01a27fb79d1076736fee24874
Signed-off-by: Etienne Bergeron <etienne.bergeron@gmail.com>
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/18785
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Tested-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
IP-Clean: Patrick Tasse <patrick.tasse@gmail.com>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>