oci8-instant-client is masked in base/use.mask while dev-db/oracle-instantclient-basic is available for amd64. Please remove mask.
Needs to stay there. Should be unmasked in amd64 profiles. This also has nothing in common w/ baselayout, re-assigning.
problem is that there is no stable version of it, which would break the dep tree. you can unmask it in /etc/portage if you're using a testing system