Introduce a flag that will enable the REPLACE
command to work correctly with an underlying
storage engine that does not report unique key
conflicts in the ascending order.

sql/handler.h:
  WL#4454 change sql_insert.cc::last_uniq_key to match keys in any order
  
  Adds the flag that will be set by a
  SE that does not report unique key
  conflicts in the ascending order.
sql/sql_insert.cc:
  WL#4454 change sql_insert.cc::last_uniq_key to match keys in any order
  
  modifies the function used for a last row
  replace optimization to check for the
  HA_DUPLICATE_KEY_NOT_IN_ORDER flag.