range: add min/max operations on ranges

    uint64_t end;   /* 1 + the last byte. 0 if range empty or ends at ~0x0LL. */

};

static inline void range_extend(Range *range, Range *extend_by)

{

    if (!extend_by->begin && !extend_by->end) {

        return;

    }

    if (!range->begin && !range->end) {

        *range = *extend_by;

        return;

    }

    if (range->begin > extend_by->begin) {

        range->begin = extend_by->begin;

    }

    /* Compare last byte in case region ends at ~0x0LL */

    if (range->end - 1 < extend_by->end - 1) {

        range->end = extend_by->end;

    }

}

/* Get last byte of a range from offset + length.

 * Undefined for ranges that wrap around 0. */

static inline uint64_t range_get_last(uint64_t offset, uint64_t len)