Issuing SELECT COUNT(*) against partitioned InnoDB table may cause
server crash.

Fixed that not all required fields were included into read_set.


mysql-test/r/partition_innodb.result:
  A test case for BUG#30583.
mysql-test/t/partition_innodb.test:
  A test case for BUG#30583.
sql/ha_partition.cc:
  Ensure that all fields of current key are included into read_set,
  as partitioning requires them for sorting
  (see ha_partition::handle_ordered_index_scan).