concurrent I_S query

There were two problem:
1) MYSQL_LOCK_IGNORE_FLUSH also ignored name locks
2) there was a race between abort_and_upgrade_locks and
   alter_close_tables
   (i.e. remove_table_from_cache and
    close_data_files_and_morph_locks)

Which allowed the table to be opened with MYSQL_LOCK_IGNORE_FLUSH flag
resulting in renaming a partition that was already in use,
which could cause the table to be unusable.

Solution was to not allow IGNORE_FLUSH to skip waiting for
a named locked table.

And to not release the LOCK_open mutex between the
calls to remove_table_from_cache and
close_data_files_and_morph_locks by merging the functions
abort_and_upgrade_locks and alter_close_tables.

mysql-test/suite/parts/r/partition_debug_sync_innodb.result:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Added test result
mysql-test/suite/parts/t/partition_debug_sync_innodb-master.opt:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Added test option
mysql-test/suite/parts/t/partition_debug_sync_innodb.test:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Added test file
sql/authors.h:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Time to be acknowledged :)
sql/ha_partition.cc:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Added DEBUG_SYNC for deterministic testing
sql/mysql_priv.h:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Renamed function since merging alter_close_tables into
  abort_and_upgrade_lock.
sql/sql_base.cc:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Changed MYSQL_LOCK_IGNORE_FLUSH to not ignore name locks
  (open_placeholder).
  
  Merged alter_close_tables into abort_and_upgrade_locks
  (and added _and_close_table to the name)
  to not release LOCK_open between remove_table_from_cache
  and close_data_files_and_morph_locks.
  
  Added DEBUG_SYNC for deterministic testing.
sql/sql_partition.cc:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Removed alter_close_tables, (merged it into
  abort_and_upgrad_lock) so that LOCK_open never is released
  between remove_table_from_cache and
  close_data_files_and_morph_locks.
sql/sql_show.cc:
  Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with
  concurrent I_S query
  
  Added DEBUG_SYNC for deterministic testing