run all available OpenCL devices

Change-Id: I6d18be3f6178003eb5153d32d4b618101ddcb3d9
Reviewed-on: https://skia-review.googlesource.com/c/191297
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed