cachel.merged_faces allocation
get_extent_fragment_face_cache_index() in `faces.c' has auto var
`cachel' and allocs `cachel.merged_faces'. I can not find passing of
`cachel.merged_faces' value (or value of `cachel.merged_faces->base')
outside this function, so that it is stored in some permanent struct
and may be freed later. However, `cachel.merged_faces' is not freed
at the end of `get_extent_fragment_face_cache_index'. Why should not
it be freed?