Bug#35161
Fixed memory leak when failing to open a partition.

Bug#20129
Added tests for verifying REPAIR PARTITION.

mysql-test/std_data/parts/t1_will_crash#P#p1_first_1024.MYD:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test
  Created by:
  CREATE TABLE t1_will_crash (
    a VARCHAR(255),
    b INT,
    c LONGTEXT,
    PRIMARY KEY (a, b))ENGINE=MyISAM
  PARTITION BY HASH (b)
  PARTITIONS 7;
  INSERT INTO t1_will_crash VALUES ...
  and then
  head -c 1024 var/master-data/test/t1_will_crash#P#p1.MYD
  into this file.
mysql-test/std_data/parts/t1_will_crash#P#p2.MYD:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after _mi_mark_file_changed in mi_write
  was done.
mysql-test/std_data/parts/t1_will_crash#P#p2.MYI:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after _mi_mark_file_changed in mi_write
  was done.
mysql-test/std_data/parts/t1_will_crash#P#p3.MYI:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after *share->write_record was done.
mysql-test/std_data/parts/t1_will_crash#P#p4.MYI:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after flush_cached_blocks
mysql-test/std_data/parts/t1_will_crash#P#p6.MYD:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after _mi_write_part_record in
  write_dynamic_record returned for the first time.
mysql-test/std_data/parts/t1_will_crash#P#p6_2.MYD:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after _mi_write_part_record in
  write_dynamic_record returned for the second time.
mysql-test/std_data/parts/t1_will_crash#P#p6_3.MYD:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  (see mysql-test/suite/parts/t/partition_repair_myisam.test)
  copy of file right after _mi_write_part_record in
  write_dynamic_record returned for the third time.
  (data file fully updated).
mysql-test/suite/parts/r/partition_recover_myisam.result:
  Bug#35161
  
  Renamed since it was a test of recover
  and to make repair free for use without
  --myisam-recover
mysql-test/suite/parts/r/partition_repair_myisam.result:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  New result file for testing CHECK/REPAIR of partitioned tables
mysql-test/suite/parts/t/partition_recover_myisam-master.opt:
  Bug#35161
  
  Renamed since it was a test of recover
  and to make repair free for use without
  --myisam-recover
mysql-test/suite/parts/t/partition_recover_myisam.test:
  Bug#35161
  
  Renamed since it was a test of recover
  and to make repair free for use without
  --myisam-recover
mysql-test/suite/parts/t/partition_repair_myisam.test:
  Bug#20129: ALTER TABLE ... REPAIR PARTITION ... not working
  
  New test file for testing CHECK/REPAIR of partitioned tables
sql/ha_partition.cc:
  Bug#35161
  
  Fix of memory leak when open of partition failed.