into 5.1

The reason for mtr warning is that collect_mysqld_features() starts mysqld with --datadir=/tmp and this 
directory does not exist on Windows.

Fix : instead of passing --datadir=$opt_vardir/tmp in collect_mysqld_features() just use --datadir=.
mysqld does not need a correct directory, just an existing one, as it is started with --help ---verbose -skip-grant-tables.

mysql-test/suite/funcs_1/r/is_columns_is.result:
  Updated test results
mysql-test/suite/pbxt/r/client_xml.result:
  Updated test results
mysys/Makefile.am:
  Added back my_port.c
storage/xtradb/buf/buf0buddy.c:
  Removed not used variables
storage/xtradb/fil/fil0fil.c:
  Added casts to fix compiler warnings

- from xtradb merge
- portability error in bitmap-t.c ( variable size  array in non-portable)

Moved some BSD string functions from Unireg

lp:~percona-dev/percona-server/release-5.1.56-12.7 percona-server-5.1.56-12.7
as of April 29, 2011.

Merged: revid:ignacio.nin@percona.com-20110427224434-e5a4kpyfwvj641q3

               FAILS WITH LIBEDIT

Fixed by checking the return value of the write()
function calls and handling the open files and fd
appropriately.


cmd-line-utils/libedit/vi.c:
  BUG#12329909 - BUILDING MYSQL WITH DEBUG SUPPORT
                 FAILS WITH LIBEDIT
  
  Added a check on the return value of the write()
  function calls.

calc_daynr() function returns negative result
if malformed date with zero year and month is used.
Attempt to calculate week day on negative value
leads to crash. The fix is return NULL for
'W', 'a', 'w' specifiers if zero year and month is used.
Additional fix for calc_daynr():
--added assertion that result can not be negative
--return 0 if zero year and month is used


mysql-test/r/func_time.result:
  test case
mysql-test/t/func_time.test:
  test case
sql-common/my_time.c:
  --added assertion that result can not be negative
  --return 0 if zero year and month is used
sql/item_timefunc.cc:
  eturn NULL for 'W', 'a', 'w' specifiers
  if zero year and month is used.

Before sorting HAVING condition is split into two parts,
first part is a table related condition and the rest of is
HAVING part. Extraction of HAVING part does not take into account
the fact that some of conditions might be non-const but
have 'used_tables' == 0 (independent subqueries)
and because of that these conditions are cut off by
make_cond_for_table() function.
The fix is to use (table_map) 0 instead of used_tables in
third argument for make_cond_for_table() function.
It allows to extract elements which belong to sorted
table and in addition elements which are independend
subqueries.


mysql-test/r/having.result:
  test case
mysql-test/t/having.test:
  test case
sql/sql_select.cc:
  The fix is to use (table_map) 0 instead of used_tables in
  third argument for make_cond_for_table() function.
  It allows to extract elements which belong to sorted
  table and in addition elements which are independend
  subqueries.

Update for previous patch according to reviewers comments.

Updated the constructors for ha_partitions to use the common
init_handler_variables functions

Added use of defines for size and offset to get better readability for the code that reads
and writes the .par file. Also refactored the get_from_handler_file function.

             FAILS ON SOLARIS

This assertion was triggered if gethostbyaddr_r cannot do a
reverse lookup on an ip address. The reason was a missing
DBUG_RETURN macro. The problem affected only debug versions of
the server.

This patch fixes the problem by replacing return with DBUG_RETURN.
No test case added.

Bug#11764671  57533: UNINITIALISED VALUES IN COPY_AND_CONVERT (SQL_STRING.CC) WITH CERTAIN CHA
When ROUND evaluates decimal result it uses Item::decimal
value as fraction value for the result. In some cases
Item::decimal is greater than real result fraction value
and uninitialised memory of result(decimal) buffer can be
used in further calculations. Issue is introduced by
Bug33143 fix. The fix is to remove erroneous assignment.


mysql-test/r/func_math.result:
  test case
mysql-test/t/func_math.test:
  test case
sql/item_func.cc:
  remove erroneous assignment

Update test case