cl_intel_unified_shared_memory says nothing about memory model

[b-sumner]

I realize that this is WIP, but the lack of discussion about the interaction with the memory model in the current draft seems to be a substantial gap that really needs to be filled.

[romanovvlad]

Tagging @jbrodman @gmlueck @bashbaug

[bashbaug]

I have an internal draft that describes many of the interactions with the memory model. It's a little old, and as I recall it's still slightly incomplete in places, but I can create a WIP pull request for additional discussion if that would be useful.