returns erroneous results

Used the wrong function when fixing 30480 which lead to
no stop on end_key resulting in duplicate results from index scan

Includes test cases for the duplicates 37327 and 37329,
Duplicate rows and bad performance/High Handler_read_next values

Recommit after merge issues

mysql-test/r/partition.result:
  Bug#35931 List partition MyISAM table returns erroneous results
  
  added test results.
mysql-test/t/partition.test:
  Bug#35931 List partition MyISAM table returns erroneous results
  
  added test for 35931, 37327 and 37329.
sql/ha_partition.cc:
  Bug#35931 List partition MyISAM table returns erroneous results
  
  HA_READ_ORDER is a index_flag, not a table_flag.
  Error made in 30480.