mariadb 11.8 wrapper: fix hlindex assertion failure in wrapper mode with FULLTEXT indexes (mroonga#977)

GitHub: mroongaGH-943

## Issue

The test `mroonga/wrapper/alter_table.change_engine` was failing with an
assertion error during ALTER TABLE operations that change MyISAM tables
with FULLTEXT indexes to Mroonga wrapper mode:

```
- saving '/home/otegami/work/cpp/mariadb-11.8.3.build/mysql-test/var/3/log/mroonga/wrapper/alter_table.change_engine/' to '/home/otegami/work/cpp/mariadb-11.8.3.build/mysql-test/var/log/alter_table.change_engine/'
***Warnings generated in error logs during shutdown after running tests: mroonga/wrapper/alter_table.change_engine

mariadbd: /home/otegami/work/cpp/mariadb-11.8.3/sql/sql_base.cc:10018: int TABLE::hlindexes_on_insert(): Assertion `s->hlindexes() == (hlindex != __null)' failed.
250910 10:31:10 [ERROR] /home/otegami/work/cpp/mariadb-11.8.3.build/sql/mariadbd got signal 6 ;
Attempting backtrace. Include this in the bug report.
```

The crash occurred during `copy_data_between_tables()` when the wrapped
handler (InnoDB) attempted to insert rows, specifically when
`TABLE::hlindexes_on_insert()` was called.

## Cause

When Mroonga operates in wrapper mode, it creates a `wrap_table_share`
structure that excludes FULLTEXT and SPATIAL indexes since these are
handled by Mroonga rather than the wrapped storage engine. The bug
occurred because:

1. The `wrap_table_share` was created by copying all fields from the
original table share
2. The `keys` field was correctly updated to reflect only
wrapper-handled keys (non-FULLTEXT, non-SPATIAL)
3. However, `total_keys` was not updated and remained at the original
value
4. This caused `hlindexes()` (calculated as `total_keys - keys`) to
return a non-zero value, incorrectly indicating that the wrapper handler
should handle FULLTEXT indexes
5. Since `hlindex` was NULL but `hlindexes() > 0`, the assertion
`s->hlindexes() == (hlindex != NULL)` failed

For example, with a table having 2 FULLTEXT indexes:
- Actual: Original table share: `hlindexes()=2`
- Expected: table share: `hlindexes()=0`

## Solution

Fixed by setting `wrap_table_share->total_keys = share->wrap_keys` in
`mrn_table.cpp`. This ensures that for the wrapper table share,
`total_keys` equals `keys`, making `hlindexes()` return 0, which
correctly indicates that the wrapper handler doesn't handle FULLTEXT
indexes.

Related MariaDB commit:
MariaDB/server@d6add9a

It also uses this solution.

Author: otegami

mrn_table.cpp

@@ -864,6 +864,9 @@ MRN_SHARE *mrn_get_share(const char *table_name, TABLE *table, int *error)
       wrap_table_share->keys = share->wrap_keys;
       wrap_table_share->key_info = share->wrap_key_info;
       wrap_table_share->primary_key = share->wrap_primary_key;
+#if defined(MRN_MARIADB_P) && (MYSQL_VERSION_ID >= 110800)
+      wrap_table_share->total_keys = share->wrap_keys;
+#endif
       wrap_table_share->keys_in_use.init(share->wrap_keys);
       wrap_table_share->keys_for_keyread.init(share->wrap_keys);
 #  ifdef MRN_TABLE_SHARE_HAVE_LOCK_SHARE