Found bug in GET_BOTH_RANGE

[Alain <alpic80@gmail.com>]

I found a bug where the data was not updated in a call to cursor get with GET_BOTH_RANGE

Here is what I did to fix it, but not 100% sure it covers everything correctly:
            rc = mc->mc_dbx->md_dcmp(data, &d2);
            if (rc) {
                if (op == MDB_GET_BOTH || rc > 0)
                    return MDB_NOTFOUND;
                data->mv_data = d2.mv_data;  //added
                data->mv_size = d2.mv_size;  //added
                rc = 0;
            }

Please confirm.

Thanks
Alain