Optimize depending sub querys
Remove valgrind warnings


libmysqld/lib_sql.cc:
  Better way to reset errors
mysql-test/mysql-test-run.sh:
  Remove wrong `
mysql-test/r/subselect.result:
  Don't use table t1
mysql-test/t/subselect.test:
  Don't use table t1
sql/item.cc:
  Indentation fix
sql/item.h:
  optimize depending sub querys
sql/item_func.cc:
  Remove warning for uninitalized data
sql/item_row.cc:
  Remove warning
sql/item_strfunc.h:
  Fixed memory overrun
sql/item_subselect.cc:
  Better debugging names
sql/log_event.cc:
  Move tmp_table_used to THD
sql/sql_base.cc:
  Move tmp_table_used to THD
sql/sql_class.cc:
  Move tmp_table_used to THD
sql/sql_class.h:
  Move tmp_table_used to THD
sql/sql_lex.cc:
  Move tmp_table_used to THD
sql/sql_lex.h:
  Move tmp_table_used to THD
sql/sql_parse.cc:
  Move tmp_table_used to THD
sql/sql_select.cc:
  optimize depending sub querys
sql/sql_table.cc:
  Move tmp_table_used to THD