Add openCL event support.

Add openCL event support.

Now use the defer execute to wait events.
If there is no user event waited, then using wait rendering to wait
GPU event complete and call the enqueue api immediately.
If there is the user events waited, then should prepare the the enqueue
data, and resume the enqueue when all user events that waited complete.
The achieve these, add the enqueue callback to user event, and add the all
user event and other wait event list to enqueue callback. When set user event
to complete, check all enqueue callbacks wait this event.

Now, clEnqueueMark/clEnqueueBarrier still not impletement, and clEnqueueMapBuffer
/clEnqueueMapImage is not consistency with spec.

Signed-off-by: Yang Rong <rong.r.yang@intel.com>
Reviewed-by: Zhigang Gong <zhigang.gong@linux.intel.com>