mysql-test/r/delete.result:
  test of new IGNORE option for DELETE
mysql-test/r/subselect.result:
  test moved to delete.test
mysql-test/t/delete.test:
  test of new IGNORE option for DELETE
mysql-test/t/subselect.test:
  test moved to delete.test
sql/sql_delete.cc:
  set errors ignoring for simple delete command
sql/sql_yacc.yy:
  add IGNORE option for DELETE command