merge fix : removed undeterministic warnings


mysql-test/r/func_gconcat.result:
  merge fix : removed undeterministic warnings
mysql-test/r/func_group.result:
  merge fix : removed undeterministic warnings
mysql-test/t/func_gconcat.test:
  merge fix : removed undeterministic warnings
mysql-test/t/func_group.test:
  merge fix : removed undeterministic warnings