Merge with MySQL 5.1.55

- Fixed some issues with partitions and connection_string, which also fixed lp:716890 "Pre- and post-recovery crash in Aria"
- Fixed wrong assert in Aria

Now need to merge with latest xtradb before pushing 

sql/ha_partition.cc:
  Ensure that m_ordered_rec_buffer is not freed before close.
sql/mysqld.cc:
  Changed to use opt_stack_trace instead of opt_pstack.
  Removed references to pstack
sql/partition_element.h:
  Ensure that connect_string is initialized
storage/maria/ma_key_recover.c:
  Fixed wrong assert

mysql-test/suite/rpl/t/rpl_temporary_errors.test

@@ -28,13 +28,13 @@ set @@global.slave_exec_mode= default;
 SHOW STATUS LIKE 'Slave_retried_transactions';
 SELECT * FROM t1;
 source include/check_slave_is_running.inc;
-DROP TABLE t1;
 
 --echo **** On Master ****
 connection master;
-SET SQL_LOG_BIN= 0;
 DROP TABLE t1;
-SET SQL_LOG_BIN= 1;
+--sync_slave_with_master
+--connection master
+
 
 # BUG#Bug #53259 Unsafe statement binlogged in statement format w/MyIsam temp tables
 #
@@ -79,6 +79,4 @@ DROP TABLE t_myisam, t_innodb;
 # "Deadlock found" set in this test case is not effective during server
 # shutdown.
 --sync_slave_with_master
-connection slave;
-STOP SLAVE;
---source include/wait_for_slave_to_stop.inc
+--source include/rpl_end.inc