"Min/Max Optimization for Queries with Group By Clause"


mysql-test/r/group_min_max.result:
  Added new test
mysql-test/t/group_min_max.test:
  Added new test & comments
sql/item.h:
  Remove processor methods that are no longer used.
sql/item_sum.cc:
  Remove processor methods that are no longer used.
sql/item_sum.h:
  Remove processor methods that are no longer used.
sql/opt_range.cc:
  - the test procedure no longer needs to build lists and to traverse the expression trees
  - all usable indexes are tested and the bes one is chosen
  - added/edited function comments
sql/sql_select.cc:
  Modified make_sum_func_list() so it can be reused in the test for MIN/MAX optimization.
sql/sql_select.h:
  Modified make_sum_func_list() so it can be reused in the test for MIN/MAX optimization.