OpenACC 3.3-NEXT has changed the way tags for copy, copyin, copyout, and
create clauses are specified, and end up adding a few extras, and
permits them as a list. This patch encodes these as bitmask enum so
they can be stored succinctly, but still diagnose reasonably.
'copy' is another that is identical in behavior on 'data' as far as
semantic analysis is concerned as the compute constructs, so this patch
adds tests and enables 'copy'.