KEY event. Partitioning wrongly claimed to be able to handle HA_DUPP_POS
when it was supported by the underlying storage engine, which resulted
in a crash when handling REPLACE statements.


mysql-test/r/partition.result:
  Add new results
mysql-test/t/partition.test:
  Add regression test
sql/ha_partition.cc:
  Fix list of table flags that are not passed through for partitioned
  tables, and add HA_DUPP_POS to that list. Also, handle HA_EXTRA_FLUSH_CACHE
  in ha_partition::extra().