Introspection: fix annotation in e_book_client_get_self
Introspection: fix annotation in e_book_client_get_self

In the previous commit I forgot to annotate the fact that
the EBookClient param is an out param too.

gcampax/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,gcampax/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,gcampax/evolution-data-server,tintou/evolution-data-server,gcampax/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server