sbitmap cleanups

[Richard Kenner]

    > !   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++'.

Sure, but it's usually more idiomatic to do it at the reference like that.