Added a test case for bug #11414.
sql_select.cc:
  Fixed bug #11414: crash on Windows with some simple
  GROUP BY queries.
  It happened to an allocation of an array containing
  0 Copy_field elements in setup_copy_fields.
  The bug had been already fixed in 5.0.


sql/sql_select.cc:
  Fixed bug #11414: crash on Windows with some simple
  GROUP BY queries.
  It happened to an allocation of an array containing
  0 Copy_field elements in setup_copy_fields.
  The bug had been already fixed in 5.0.
mysql-test/t/group_by.test:
  Added a test case for bug #11414.
mysql-test/r/group_by.result:
  Added a test case for bug #11414.