common/iobuf.c: Refactor code to not need the desc field.
* common/iobuf.h (struct iobuf_struct): Remove field desc. * common/iobuf.c (iobuf_desc): New function. When a filter's description is needed, use this instead of the filter's desc field.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>.