Demote 'OpenCL not found' message WARNING -> STATUS
I noticed that NICOS displays for athena are highlighting this warning (i.e. builds are going yellow because of it). Since it occurs in CI builds, I'm supposing that it's not really an issue that OpenCL has not been found. Hence it seems to me that WARNING
is too strong.
This is a resubmission of !140 (merged) which targeted the wrong branch.