disable decoding of table name if the table is internal temporary table


mysql-test/r/drop.result:
  test result
mysql-test/t/drop.test:
  test case
sql/sql_db.cc:
  check is the name is internal tmp table name
sql/sql_table.cc:
  disable decoding of table name if the table is internal temporary table
sql/table.h:
  added flag which is true when table name is the name of internal temporary table