STRING_RESULT argument

There is a "magic" number for precision : NOT_FIXED_DEC. 
This means that the precision is not a fixed number.
But this constant was re-defined in several files and 
was not available to the UDF developers.

Moved the NOT_FIXED_DEC definition to the correct header
and removed the redundant definitions.

into  kaamos.(none):/data/src/opt/mysql-5.1-opt

into  kaamos.(none):/data/src/opt/mysql-5.1-opt

into  kaamos.(none):/data/src/opt/mysql-5.1-opt

into  kaamos.(none):/data/src/opt/mysql-5.0-opt

into  kaamos.(none):/data/src/opt/bug31781/my51

                    with errno 17

my_create() did not perform any checks for the case when a file is
successfully created by a call to open(), but the call to
my_register_filename() later fails because the number of open files
has exceeded the my_open_files limit. This can happen on platforms 
which do not have getrlimit(), and hence we do not know the real limit
for open files. In such a case an error was returned to a caller
although the file has actually been created. Since callers assume
my_create() to return an error only when it failed to create a file,
they did not perform any cleanups, leaving an 'orphaned' file on the
file system.

Fixed by adding a check for the above case to my_create() and ensuring
the newly created file is deleted before returning an error.

Creating a deterministic test case in the test suite is impossible,
because the exact steps required to reproduce the above situation
depend on the platform and/or environment (OS per-user limits, queries
executed by previous tests, startup parameters). The patch was
manually tested on Windows using examples posted in the bug report.

into  mysql.com:/home/gluh/MySQL/mysql-5.1-opt

into  host.loc:/home/uchum/work/5.0-opt

into  host.loc:/home/uchum/work/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.0-opt

                  and Item_direct_ref constructor calls.

Order of ref->field_name and ref->table_name arguments
is of Item_ref and Item_direct_ref in the fix_inner_refs
function is inverted.

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  mysql.com:/home/gluh/MySQL/Merge/5.0-opt

added new function test_if_data_home_dir() which checks that
path does not contain mysql data home directory.
Using of mysql data home directory in
DATA DIRECTORY & INDEX DIRECTORY is disallowed.

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  host.loc:/home/uchum/work/5.1-opt

into  host.loc:/home/uchum/work/5.0-opt

                  Assertion `0' failed

If ROW item is a part of an expression that also has
aggregate function calls (COUNT/SUM/AVG...), a
"splitting" with an Item::split_sum_func2 function
is applied to that ROW item.
Current implementation of Item::split_sum_func2
replaces this Item_row with a newly created
Item_aggregate_ref reference to it.
Then the row cache tries to work with the
Item_aggregate_ref object as with the Item_row object:
row cache calls row-emulation methods such as cols and
element_index. Item_aggregate_ref (like it's parent
Item_ref) inherits dummy implementations of those
methods from the hierarchy root Item, and call to
them leads to failed assertions and wrong data
output.

Row-emulation virtual functions (cols, element_index, addr,
check_cols, null_inside and bring_value) of Item_ref have
been overloaded to forward calls to an underlying item
reference.

into  magare.gmz:/home/kgeorge/mysql/work/B34747-5.1-opt

into  magare.gmz:/home/kgeorge/mysql/autopush/B34747-5.0-opt

added new function test_if_data_home_dir() which checks that
path does not contain mysql data home directory.
Using of 'mysql data home'/'any db name' in
DATA DIRECTORY & INDEX DIRECTORY is disallowed

Was a double-free of the Unique member of Item_func_group_concat.
This was not causing a crash because the Unique is a descendent of
Sql_alloc.
Fixed to free the Unique only if it was allocated for the instance 
of Item_func_group_concat it was referenced from

into  kaamos.(none):/data/src/opt/mysql-5.1-opt

into  kaamos.(none):/data/src/opt/mysql-5.0-opt

into  kaamos.(none):/data/src/opt/bug33834/my51-bug33834

the patch for bug #33834.

into  mysql.com:/home/hf/work/25097/my51-25097

into  mysql.com:/home/hf/work/25097/my50-25097