lttng: Add Callstack View support for UST traces

lttng: Add Callstack View support for UST traces

UST traces using the lttng-ust-cyg-profile library will contain events
about function entries and exists. We can leverage(!) this information
to populate the generic TMF Callstack view.

For now it will only print the function addresses. Until the whole
function-names-in-the-trace debate is resolved upstream, we will provide
a mechanism to import a mapping file manually. This will come in a
separate commit.

Change-Id: I03b461ef9e863ddb6988907514e96bb3db3eaef9
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/16394
Tested-by: Hudson CI
Reviewed-by: Genevieve Bastien <gbastien+lttng@versatic.net>
IP-Clean: Genevieve Bastien <gbastien+lttng@versatic.net>