When analyzing the possible index use cases the server was re-using an internal structure.
This is wrong, as this internal structure gets updated during the analysis.
Fixed by making a copy of the internal structure for every place it needs to be used.
Also stopped the generation of empty SEL_TREE structures that unnecessary 
complicate the analysis.

Repush of change to fix tests on Pushbuild.

Server created "arc" directories inside database directories and
maintained there useless copies of .frm files.

Creation and renaming procedures of those copies as well as
creation of "arc" directories has been discontinued.
Removal procedure has been kept untouched to be able to
cleanup existent database directories by the DROP DATABASE
query. Also view renaming procedure has been updated to remove
these directories.

     JOIN for the subselect wasn't cleaned if we came upon an error
     during sub_select() execution. That leads to the assertion failure
     in close_thread_tables()

     part of the 6.0 code backported

per-file comments:
  mysql-test/r/sp-error.result
Bug#37949 Crash if argument to SP is a subquery that returns more than one row 
    test result

  mysql-test/t/sp-error.test
Bug#37949 Crash if argument to SP is a subquery that returns more than one row 
    test case

  sql/sp_head.cc
Bug#37949 Crash if argument to SP is a subquery that returns more than one row 
    lex->unit.cleanup() call added if not substatement

Bug#38311 - Fix of some cruft from remove_files in ndb_autodiscover.test, clean up of distinct.test,
and replacing error numbers with error names.

            
A stored procedure involving substrings could crash the server on certain
platforms because of invalid memory reads.
          
During storing the new blob-field value, the cached value's address range
overlapped that of the new field value. This caused problems when the 
cached value storage was reallocated to provide access for a new 
characater set representation. The patch checks the address ranges, and if
they overlap, the new field value is copied to a new storage before it is
converted to the new character set.

Substituted use of MTR's remove_file function in the tests
Started with 5.0 tree and will clean up any offenders discovered during upmerge.

no conflicts

      
The fix for bug 31887 was incomplete : it assumes that all the 
field types returned by the IS_NUM macro are descendants of 
Item_num and tries to zero-fill the values before doing constant
substitution with such fields when they are compared to constant string
values.
The only exception to this is Field_timestamp : it's in the IS_NUM
macro, but is not a descendant of Field_num.
Fixed by excluding timestamp fields (Field_timestamp) when zero-filling
when converting the constant to compare with to a string.
Note that this will not exclude the timestamp columns from const 
propagation.

Bug#37114: sql_mode NO_BACKSLASH_ESCAPES does not work properly with LOAD DATA      Bug#37114: sql_mode NO_BACKSLASH_ESCAPES does not work properly with LOAD DATA INFILE

tweaked test to make embedded server happy

NO_BACKSLASH_ESCAPES was not heeded in LOAD DATA INFILE
and SELECT INTO OUTFILE.  It is now.

Details:
- backport of some improvements which prevent sporadic
  failures from 5.1 to 5.0
- @@GLOBAL.CONCURRENT_INSERT= 0 also for slave server
- --sorted_result before all selects which have result
  sets with more than one row
- Replace error numbers by error names

Correct usage of strncat() in get_symbol_path()

3rd parameter to strncat is changed to be count of 
remaining bytes in the output buffer minus 1.

Moved fix for this bug to 5.0 as other mysqldump bugs seem tied to concurrent_insert being on
Setting concurrent_insert off during this test as INSERTs weren't being 
completely processed before the calls to mysqldump, resulting in failing tests.

Altered .test file to turn concurrent_insert off during the test and to restore it
to whatever the value was at the start of the test when complete.

Re-recorded .result file to account for changes to variables in the test.

The problem here is that symbols can not be loaded, because symbol
path is not set and  default path does not include the directory
where PDB is located.

The problem is _not_ reproducible on the same machine where
mysqld.exe is built - if PDB is not found in the symbol path,
dbghelp would fallback to fully qualified PDB path as given in the
executable header and on the build host this will succeed.

The solution is to calculate symbol path and pass it to SymInitialize()
call.

mysqldump creates stand-in tables before dumping the actual view.
Those tables were of the default type; if the view had more columns
than that (a pathological case, arguably), loading the dump would
fail. We now make the temporary stand-ins MyISAM tables to prevent
this.

Problem: <=> operator may return wrong results 
comparing NULL and a DATE/DATETIME/TIME value.

Fix: properly check NULLs.

Problem: SELECT ... REGEXP BINARY NULL may lead to server crash/hang.

Fix: properly handle NULL regular expressions.

in open_table()

Problem: repeating "CREATE... ( AUTOINCREMENT) ... SELECT" may lead to
an assertion failure.

Fix: reset table->auto_increment_field_not_null after each record 
writing.

  INSERT .. SELECT .. ON DUPLICATE KEY UPDATE col=DEFAULT

In order to get correct values from update fields that
belongs to the SELECT part in the INSERT .. SELECT .. ON
DUPLICATE KEY UPDATE statement, the server adds referenced
fields to the select list. Part of the code that does this
transformation is shared between implementations of
the DEFAULT(col) function and the DEFAULT keyword (in
the col=DEFAULT expression), and an implementation of
the DEFAULT keyword is incomplete.

Bug#33031 app linked to libmysql.lib crash if run as service in vista under 
localsystem
  

There are some problems using DllMain hook functions on Windows that 
automatically do global and per-thread initialization for libmysqld.dll

1)per-thread initialization(DLL_THREAD_ATTACH)
MySQL internally counts number of active threads that and causes a delay in in 
my_end() if not all threads are exited. But,there are threads that can be 
started either by Windows internally (often in TCP/IP scenarios) or by user 
himself - those threads are not necessarily using libmysql.dll functionality, 
but nonetheless the contribute to the count of open threads.

2)process-initialization (DLL_PROCESS_ATTACH)
my_init() calls WSAStartup that itself loads DLLs and can lead to a deadlock in 
Windows loader.

Fix is to remove dll initialization code from libmysql.dll in general case. I
still leave an environment variable LIBMYSQL_DLLINIT, which if set to any value 
will cause the old behavior (DLL init hooks will be called). This env.variable 
exists only to prevent breakage of existing Windows-only applications that 
don't do mysql_thread_init() and work ok today. Use of LIBMYSQL_DLLINIT is 
discouraged and it will be removed in 6.0