WL#6392 : Upgrade to Transactional Data Dictionary

Code cleanup:

Remove unnecessary declaration of function load_db_schema_collation()
from dd_upgrade.h file.

Author: abhi5466

sql/dd/dd_upgrade.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -73,17 +73,6 @@ bool find_files_with_metadata(THD *thd, const char *dbname,
 */
 bool find_schema_from_datadir(THD *thd, std::vector<String_type> *db_name);
 
-/**
-  Get collation id for database collation from db.opt file.
-
-  @param[out] collation_id  Store collation id.
-  @param[in]  db_opt_path   Path of db.opt file.
-
-  @retval false  ON SUCCESS
-  @retval true   ON FAILURE
-*/
-bool load_db_schema_collation(uint *collation_id, const LEX_STRING *db_opt_path);
-
 /**
   Create entry in mysql.schemata for all the folders found in data directory.
   If db.opt file is not present in any folder, that folder will be treated as