Remove g_type_init() calls.

https://git.gnome.org/browse/glib/commit/?id=1dc774a653e992e1153fbed16f90097fa8db467f
https://git.gnome.org/browse/vala/commit/?id=f1fbafdfdc91fadaa57d2e073fc29cc6804d6ae3

Review URL: https://codereview.appspot.com/9727047