auto_increment on duplicate entry

The bug was that when INSERT_ID was used and the storage
engine was told to release any reserved but not used
auto_increment values, it set the highest auto_increment
value to INSERT_ID.

The fix was to check if the auto_increment value was forced
by user (INSERT_ID) or by slave-thread, i.e. not auto-
generated. So that it is only allowed to release generated
values.

mysql-test/r/partition_error.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  updated result
mysql-test/suite/parts/inc/partition_auto_increment.inc:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added test
mysql-test/suite/parts/r/partition_auto_increment_archive.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that archive does only allow increasing
  auto_increment values
mysql-test/suite/parts/r/partition_auto_increment_blackhole.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that blackhole accepts all inserts :)
mysql-test/suite/parts/r/partition_auto_increment_innodb.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that innodb rolls back inserts on error,
  but keeps the auto_increment value.
mysql-test/suite/parts/r/partition_auto_increment_memory.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that memory and myisam inserts all rows
  before the error.
mysql-test/suite/parts/r/partition_auto_increment_myisam.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that memory and myisam inserts all rows
  before the error.
mysql-test/suite/parts/r/partition_auto_increment_ndb.result:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added result, note that NDB does not seem to handle
  INSERT_ID as other engines. (Martin will look into it).
mysql-test/t/partition_error.test:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  Added test
sql/ha_partition.cc:
  Bug#50392: insert_id is not reset for partitioned tables
  auto_increment on duplicate entry
  
  If the next_insert_id comes from non generated (i.e
  forced by INSERT_ID or slave-thread) then we cannot
  lower the reserved auto_increment value, since it have
  not reserved any values.