The documentation says 'This array should be freed with g_free() when
it is no longer needed', which really translates to (transfer
container) in introspection annotation jargon.
https://bugzilla.gnome.org/show_bug.cgi?id=677407
/**
* pango_font_family_list_faces:
* @family: a #PangoFontFamily
- * @faces: (out) (allow-none) (array length=n_faces): location to store an array of pointers to #PangoFontFace
- * objects, or %NULL. This array should be freed with g_free()
- * when it is no longer needed.
+ * @faces: (out) (allow-none) (array length=n_faces) (transfer container):
+ * location to store an array of pointers to #PangoFontFace objects,
+ * or %NULL. This array should be freed with g_free() when it is no
+ * longer needed.
* @n_faces: (out): location to store number of elements in @faces.
*
* Lists the different font faces that make up @family. The faces