Partitioning is the creation of sub-devices. Also add reference
counting for CL objects, which is needed now for sub-devices.

Also fix CL print format strings, since cl_ulong is actually
always 64 bit and not unsigned long.

Bug: angleproject:5904
Change-Id: I006699fad2f953ce312bca87c9b6362b5d77a18a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2880665
Commit-Queue: John Plate <jplate@google.com>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>