Fix for BUG#6303 + fix for discovered bug with sub-queries when analyzin queries for MIN/MAX optimization (WL#1724).


BitKeeper/etc/ignore:
  Added stamp-h1.in stamp-h2.in to the ignore list
mysql-test/t/group_min_max.test:
  - Added test for BUG#6303
  - Added test for MIN/MAX optimizable queries with subqueries
sql/opt_range.cc:
  - check_group_min_max_predicates should not be called when there is no MIN/MAX function
  - skip queries from GROUP BY with MIN/MAX optimization when there is a subselect in the WHERE clause