0a5d415c1d
For addMarker, assume T1 comes in first and enqueues a command C1.
Before T1 grabs the event_::lock_ it gets preempted. At this time,
T2 comes in, enqueues C2 and grabs the lock_ and updates event_. Now T1
wakes up and updates a older command C1 for the event.
Change-Id: Ia423782b23026302c40976385623cfdede32d70b
[ROCm/clr commit: b1657c4159]