Kadu gadu_protocol and jabber_protocol plugins require app-crypt/qca-ossl run-time presence for certain features to work. Though, due to upstream omission, they don't warn when qca-ossl not found and instead fail silently (jabber_protocol) or crash (gadu_protocol). It also places ssl USE flag under question as all its dependencies are actually always required.
Thanks for reporting, USE flag removed.