blobtool: Wrap in/out GString pair in a struct
blobtool: Wrap in/out GString pair in a struct

- Wrap in/out GString pair in a struct.  This only affects functions
whose in parameter is a GString rather than a char *.

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr