few small MySQL bugs/issues that impact the engines, as discussed in the SE summit

* remove handler::index_read_last()
* create handler::keyread_read_time() (was get_index_only_read_time() in opt_range.cc)
* ha_show_status() allows engine's show_status() to fail
* remove HTON_FLUSH_AFTER_RENAME
* fix key_cmp_if_same() to work for floats and doubles
* set table->status in the server, don't force engines to do it
* increment status vars in the server, don't force engines to do it

mysql-test/r/status_user.result:
  correct test results - innodb was wrongly counting internal
  index searches as handler_read_* calls.
sql/ha_partition.cc:
  compensate for handler incrementing status counters -
  we want to count only calls to underlying engines
sql/handler.h:
  inline methods moved to sql_class.h
sql/key.cc:
  simplify the check
sql/opt_range.cc:
  move get_index_only_read_time to the handler class
sql/sp.cc:
  don't use a key that's stored in the record buffer -
  the engine can overwrite the buffer with anything, destroying the key
sql/sql_class.h:
  inline handler methods that need to see THD and TABLE definitions
sql/sql_select.cc:
  no ha_index_read_last_map anymore
sql/sql_table.cc:
  remove HTON_FLUSH_AFTER_RENAME
sql/table.cc:
  set HA_CAN_MEMCMP as appropriate
sql/tztime.cc:
  don't use a key that's stored in the record buffer -
  the engine can overwrite the buffer with anything, destroying the key
storage/myisam/ha_myisam.cc:
  engines don't need to update table->status or use ha_statistic_increment anymore
storage/myisam/ha_myisam.h:
  index_read_last_map is no more

sql/key.cc

@@ -278,8 +278,7 @@ bool key_cmp_if_same(TABLE *table,const uchar *key,uint idx,uint key_length)
       key++;
       store_length--;
     }
-    if (key_part->key_part_flag & (HA_BLOB_PART | HA_VAR_LENGTH_PART |
-                                   HA_BIT_PART))
+    if (!(key_part->key_part_flag & HA_CAN_MEMCMP))
     {
       if (key_part->field->key_cmp(key, key_part->length))
 	return 1;