sbitmap cleanups

[John Marshall]

Richard Kenner writes:
> *************** sbitmap_a_subset_b_p (a, b)
[...]
> !   for (ap = a->elms, bp = b->elms, i = 0; i < a->size; i++)
> !     if ((*ap++ | *bp++) != *bp)
> !       return 0;

Uh, I didn't notice any sequence points...  you could just put the
increments up beside the `i++'.

    John