tls_client test: Catch an exception
tls_client test: Catch an exception

* giomm_tls_client/main.c: Catch an exception because that is what
actually happens when there is no internet connection.
It still fails in that case, however.

GNOME/glibmm,johne53/MB3Glibmm,johne53/MB3Glibmm,johne53/MB3Glibmm,GNOME/glibmm,GNOME/glibmm,johne53/MB3Glibmm,GNOME/glibmm,GNOME/glibmm