mariadb_rpl_fetch() crashes if table is partitioned

Following the bug I reported in CONC-657, I tested it in Connector/C 3.3.8.
Unfortunately the fix does not match my proposed fix, and still crashes.

Note that I proposed to do this:
ev += (rpl_event->event.rows.extra_data_size - 2);
However, 3.3.8 does this, which is totally wrong:
ev+= rpl_event->event.rows.extra_data_size;

I tested it on a MySQL 8.0 database with a table that is partitioned by range.

CREATE TABLE `partitions` (
`id` int NOT NULL PRIMARY KEY,
`str` varchar(25) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/*!50100 PARTITION BY RANGE (`id`)
(PARTITION p0 VALUES LESS THAN (10) ENGINE = InnoDB,
PARTITION p1 VALUES LESS THAN (20) ENGINE = InnoDB,
PARTITION p2 VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */;