Removed not used functions and variables

Author: montywi

sql/sql_class.h

@@ -148,7 +148,6 @@ enum enum_binlog_row_image {
 
 extern char internal_table_name[2];
 extern char empty_c_string[1];
-extern LEX_STRING EMPTY_STR;
 extern MYSQL_PLUGIN_IMPORT const char **errmesg;
 
 extern bool volatile shutdown_in_progress;

sql/table.h

@@ -2901,7 +2901,6 @@ enum open_frm_error open_table_def(THD *thd, TABLE_SHARE *share,
 void open_table_error(TABLE_SHARE *share, enum open_frm_error error,
  int db_errno);
 void update_create_info_from_table(HA_CREATE_INFO *info, TABLE *form);
-bool check_and_convert_db_name(LEX_STRING *db, bool preserve_lettercase);
 bool check_db_name(LEX_STRING *db);
 bool check_column_name(const char *name);
 bool check_table_name(const char *name, size_t length, bool check_for_path_chars);