Remove g_type_init() calls

Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().

Remove those uses, as they are no longer required.

https://bugzilla.gnome.org/show_bug.cgi?id=686161

gio/tests/gdbus-example-objectmanager-server.c

@@ -139,8 +139,6 @@ main (gint argc, gchar *argv[])
   GMainLoop *loop;
   guint id;
 
-  g_type_init ();
-
   loop = g_main_loop_new (NULL, FALSE);
 
   id = g_bus_own_name (G_BUS_TYPE_SESSION,