Lifted the limitation that hash join could not be used over 
varchar fields with non-binary collation.

- Merge with 5.3-main

set thd->password appropriately also for cases when a user was not found.

- Fixes for the second fix: take into account case where we don't need to save/restore the scan.

Switch from "Disable identical key handling optimization when
  IndexConditionPushdown is used" approach
To 
 an approach where we save/restore index tuple and so can use index condition pushdown.

mwl#21.

It was missing from EXTRA_DIST in Makefile.am.

 - Address Monty's review feedback, portion 3

- Address Monty's review feedback, portion 2

- Better warnings

Analysis:
The assert failed because st_select_lex::print() was called for subqueries
as follows:

Item_subselect::print() ->
  subselect_single_select_engine::print() -> st_select_lex::print()

It was Item_subselect::fix_fields() that set the thd by calling set_thd(),
so when this print() was called before fix_fields(), subselect_engine::thd
was NULL.

Solution:
The patch makes all constructors of all subselect_engine classes to take
a THD parameter. The default subselect_single_select_engine engine is created
early during parse time, in the Item_subselect::init call, so we pass the
correct THD object already at this point.

- Address review feedback: change return type of RANGE_SEQ_IF::next()

(Includes patch for overrun detected by valgrind thanks to previous my_alloca() -> my_malloc() patch)

mysys/thr_lock.c:
  Fixed typo that caused compile failure

- This allows us to detect missing my_afree() calls and also find overruns (when running with valgrind) to alloca() areas.
- Added missing my_afree() calls
- Fixed wrong call to my_afree()


include/my_sys.h:
  When compiling with valgrind, change my_alloca() to use my_malloc()
mysql-test/suite/innodb/t/innodb_bug57255.test:
  Speed up taste case (patch from Stewart Smith)
mysql-test/suite/innodb_plugin/t/innodb_bug57255.test:
  Speed up taste case (patch from Stewart Smith)
sql/ha_partition.cc:
  Removed casts from my_afree()
sql/opt_range.cc:
  Add missing my_afree() calls.
storage/maria/ma_rt_split.c:
  Fixed wrong parameter to my_afree()

pointers.

storage/maria/ma_check.c:
  Allocate also memory for nodflag and transid's
storage/maria/ma_write.c:
  Allow nodflag and transid as part of key.
  (This has nothing to do with the bug report, but it's a safer check).
storage/maria/maria_def.h:
  Define MARIA_MAX_POINTER_LENGTH (length of pointer to node)
  Added node pointer length to MARIA_INDEX_OVERHEAD_SIZE, as this is part of the key.
  (Safety fix)

Made archive.test a bit more safe



mysql-test/r/archive.result:
  Added removal of files to make rerun of failed test work
mysql-test/t/archive.test:
  Added removal of files to make rerun of failed test work
mysys/thr_lock.c:
  Better warning message if lock test fails

Also:
Changed the value of TIME_FOR_COMPARE_ROWID to make it the same as for MWL 21.
Changed some queries in range_vs_index_merge.test to make them generate
the same plans as earlier.

- Make Mrr_ordered_index_reader() save the rowid across scan interruptions

Also
- Fix compiler warning for setup_buffer_sizes()
- Add commented key_copy/key_restore for better handling of a similar issue
  with index record being destroyed by scan interruption (which causes 
  incorrect evaluation of pushed index condition later on).

Fixed compiler warning

mysql-test/r/named_pipe.result:
  Fixed test results for windows builds
mysql-test/r/shm.result:
  Fixed test results for windows builds
sql/item_cmpfunc.cc:
  Fixed compiler warning about uninitialized "first"

MBug#687320: Fix sporadic test failures in innodb_mysql.test and partition_innodb_semi_consistent.test

Problem is that these tests run with --innodb-lock-wait-timeout=2 in .opt
(and this is necessary as built-in innodb does not allow to change this
dynamically). This cases another part of the test to occasionally time
out an UPDATE, which subsequently caused the test case to timeout due to
waiting for a condition (successful UPDATE) that never occurs.

Fixed by re-trying the update in case of timeout.

Tested by inserting a sleep() in the connection that the UPDATE is waiting
for, and checking that the retry loops a couple of times until the other
connection is done and COMMITs.