MDEV-13228 Assertion `n < rec_offs_n_fields(offsets)' failed in rec_g…

…et_nth_field_offs upon crash recovery with compressed table

In my preparatory patch for MDEV-12288, there was an off-by-one
array initialization error that affected debug builds.

storage/innobase/btr/btr0cur.cc

@@ -4601,15 +4601,15 @@ btr_cur_parse_del_mark_set_clust_rec(
 		btr_rec_set_deleted_flag(rec, page_zip, val);
 		ut_ad(pos <= MAX_REF_PARTS);
 
-		ulint offsets[REC_OFFS_HEADER_SIZE + MAX_REF_PARTS + 2];
+		ulint offsets[REC_OFFS_HEADER_SIZE + MAX_REF_PARTS + 3];
 		rec_offs_init(offsets);
 		mem_heap_t*	heap	= NULL;
 
 		if (!(flags & BTR_KEEP_SYS_FLAG)) {
 			row_upd_rec_sys_fields_in_recovery(
 				rec, page_zip,
 				rec_get_offsets(rec, index, offsets,
-						pos + 1, &heap),
+						pos + 2, &heap),
 				pos, trx_id, roll_ptr);
 		} else {
 			/* In delete-marked records, DB_TRX_ID must