- Make send_row_on_empty_set() return FALSE when simplify_cond() has found out
  that HAVING is always FALSE
re-committing to put the fix into 5.0 and 5.1

mysql-test/r/group_by.result:
  BUG#38072: Wrong result: HAVING not observed in a query with aggregate
  - Testcase
mysql-test/t/group_by.test:
  BUG#38072: Wrong result: HAVING not observed in a query with aggregate
  - Testcase
sql/sql_select.h:
  BUG#38072: Wrong result: HAVING not observed in a query with aggregate
  - Make send_row_on_empty_set() return FALSE when simplify_cond() has found out
    that HAVING is always FALSE