Add UserBuffer to customOp with true

Add UserBuffer to customOp with true

[Version] 0.0.5-0
[Issue type] bug fix

In mlapi, snpe filter causes segfault while handling multiple outputs
and the UserBuffer customOp is a solution for the issue.
This commit is for inference-engine-mlapi to apply UserBuffer customOp to mlapi.
Note that the UserBuffer customOp is valid only for snpe.
If an invalid customOp is given, for example the UserBuffer customOp for
tflite, mlapi ignore it.

Change-Id: Id8bb0e3a83b8b72b73258dd1c8e1325bf3532650
Signed-off-by: Tae-Young Chung <ty83.chung@samsung.com>