mysql-test/r/derived.result:
  test for a bug fix which caused a deadlock !
  Also test for a bug fix with using() on derived tables
mysql-test/r/subselect.result:
  correcting previous changes caused by a bug ..
mysql-test/t/derived.test:
  test for a bug fix which caused a deadlock !
  Also test for a bug fix with using() on derived tables
mysql-test/t/subselect.test:
  corrections of previous changes caused by a bug ..
sql/sql_base.cc:
  A for for a bug which caused a deadlock !
  Also fix for a bug with using() on derived tables
sql/sql_derived.cc:
  code cleanup
sql/sql_lex.cc:
  fix for deadlock