add hello-opencl

This is a little hello world for OpenCL.

Change-Id: I9502407dab75694a19e97832bcfe33f47cbd97e9
Reviewed-on: https://skia-review.googlesource.com/136223
Commit-Queue: Allan MacKinnon <allanmac@google.com>
Reviewed-by: Allan MacKinnon <allanmac@google.com>
3 files changed