They are semantically wrong anyway because they work on drawable,
assuming that the drawable is encoded in whatever non-RGB pixel (while
getting data in R'G'B'A format). This is just an internal trick of the
file-dds plug-in which converts DDS data internally instead of having
babl doing the job by making appropriate formats.

Anyway we should definitely not expose such procedure publicly. I am not
deleting the code directly, just hiding it away in `#if 0` for now.