For being able to build the tests via source archives, the 'base'
library must be denoted as dependency explicitely in their 'target.mk' file.
This is because when building archives, the API dependencies of used APIs are
not taken into account.
This is a follow-up commit to "Increase default warning level", which
overrides Genode's new default warning level for targets contained in
higher-level repositories. By explicitly whitelisting all those targets,
we can selectively adjust them to the new strictness over time - by
looking out for 'CC_CXX_WARN_STRICT' in the target description files.
Issue #465