[ticket/12387] Cleanup *_free_result call and remove @ on that call

PHPBB3-12387
[ticket/12387] mssql_query return true if a select query returns 0 row

PHPBB3-12387
[ticket/12387] Remove unnecessary checks

PHPBB3-12387
[ticket/12387] Use the hash as query_id for caching

PHPBB3-12387
[ticket/12387] Fix \phpbb\db\driver\mysqli::sql_freeresult

PHPBB3-12387
[ticket/12387] Fix a call to sql_freeresult in full_text_native

PHPBB3-12387
Merge pull request #2637 from Nicofuma/ticket/12387

[ticket/12387] Cleanup *_free_result call and remove @ on that call

* Nicofuma/ticket/12387:
  [ticket/12387] Fix a call to sql_freeresult in full_text_native
  [ticket/12387] Fix \phpbb\db\driver\mysqli::sql_freeresult
  [ticket/12387] Use the hash as query_id for caching
  [ticket/12387] Remove unnecessary checks
  [ticket/12387] mssql_query return true if a select query returns 0 row
  [ticket/12387] Cleanup *_free_result call and remove @ on that call