malloc types into a structure, a pointer to which is passed around,
instead of an int constant. Allow the limit to be adjusted when the
malloc type is defined, or with a function call, as suggested by
Jonathan Stone.
raidframevar.h - contains bits of rf_types.h, rf_layout.h,
rf_netbsd.h, rf_raid.h, and rf_decluster.h.
raidframeio.h - contains the bits needed for doing IOCTL's w/
RAIDframe.
These bits will be visible to userland.