Follow-up to b84edbf2; (IV) the IVdf.

Since there could be platforms where sizeof(SSize_t) < sizeof(IV).
(E.g. IRIX n32 model: 64-bit integers but 32-bit pointers.)

(Note: in addition to %zd being a C99 thing,
 googling says %zd is not well supported in VC).
More (void*) for %p.

(Note: looks like char* "decay" into void* without casting needed?)