Fix to remove engine dependency from handler.cc file, the last one for functions.

sql/ha_innodb.cc:
  Added new function to handlerton.
sql/handler.cc:
  Removed Innodb dependency (last remaining function call).
sql/handler.h:
  Added additional function for engines who need to know about client communication.

sql/handler.h

@@ -580,6 +580,7 @@ typedef struct
    void (*binlog_log_query)(THD *thd, enum_binlog_command binlog_command,
                             const char *query, uint query_length,
                             const char *db, const char *table_name);
+   int (*release_temporary_latches)(THD *thd);
 } handlerton;
 
 extern const handlerton default_hton;