Fixed bug #11479.
  The JOIN::reinit method cannot call setup_tables
  after the optimization phase since this function
  removes some optimization settings for joined
  tables. E.g. it resets values of the null_row flag to 0.
subselect.result, subselect.test:
  Added a test case for bug #11479.


mysql-test/t/subselect.test:
  Added a test case for bug #11479.
mysql-test/r/subselect.result:
  Added a test case for bug #11479.
sql/sql_select.cc:
  Fixed bug #11479.
  The JOIN::reinit method cannot call setup_tables
  after the optimization phase since this function
  removes some optimization settings for joined
  tables. E.g. it resets values of the null_row flag to 0.