delayed_close_free() calls g_object_unref() on a variable that is
expected to possibly contain NULL (as indicated by the fact that the
NULL case is handled in my_slow_close_output_stream_close_async()).
This is dead code right now (due to a bug in GDBus), which is why it
isn't actually causing a failure. It should still be fixed, however.
https://bugzilla.gnome.org/show_bug.cgi?id=743990
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