lttng: additional definitions for lttng 2.7 and 2.8

lttng: additional definitions for lttng 2.7 and 2.8

* New event sched_waking (for upcomming lttng 2.8 and linux > 4.3)
* Modified event names in lttng 2.7 for softirqs
  (softirq_entry renamed to irq_softirq_entry)

Change-Id: I0c5acd0e201e41ad7f2cf6749cc2105d41523f3f
Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Reviewed-on: https://git.eclipse.org/r/59230
Reviewed-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@efficios.com>