BUG#28341 - Security issue still in library loading

Added required option files to rpl_udf test.

into  mysql.com:/home/svoj/devel/mysql/BUG28341/mysql-5.1-engines

UDF can be created from any library in any part of the server
LD_LIBRARY_PATH.

Allow to load udfs only from plugin_dir.
On windows, refuse to open udf in case it's path contains a slash.

No good test case for this bug because of imperfect error message
that includes error code and error string when it fails to dlopen a
library.

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.0-engines

BUG#25712 - insert delayed and check table run together report crashed
            tables
Fixed wrongly applied patch.

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.0-engines

BUG#25712 - insert delayed and check table run together report
            crashed tables

Let MY_THREADSAFE have distinct value. Some functions call my_seek
passing MyFlags argument directly to it. This may cause unnecessary
locks, which may finally lead to a dead-lock (specifically see my_lock).

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG25712/mysql-5.0-engines

            tables

In case system doesn't have native pread/pwrite calls (e.g. Windows)
and there is CHECK TABLE runs concurrently with another statement that
reads from a table, the table may be reported as crashed.

This is fixed by locking file descriptor when my_seek is executed on
MyISAM index file and emulated pread/pwrite may be executed concurrently.

Affects MyISAM tables on platforms that do not have native
pread/pwrite calls (e.g. Windows).

No deterministic test case for this bug.

            can crash under load
Post-post-review fixes.
Fixed a typo == -> =
Optimized normal flush at end of statement (FLUSH_KEEP),
but let other flush types be stringent.
Added comments.
Fixed debugging.

into  chilla.local:/home/mydev/mysql-5.1-bug17332

into  mysql.com:/home/svoj/devel/mysql/BUG27998/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG27998/mysql-5.0-engines

  "Blackhole tables don't honor table locks"
  Implement neccessary shared lock structure for table locks.
  Imported test case created by Giuseppe Maxia

into  xiphis.org:/home/antony/work2/mysql-5.1-merge

into  mysql.com:/d2/hf/mrg/mysql-5.1-opt

into  mysql.com:/d2/hf/mrg/mysql-5.0-opt

into  mysql.com:/d2/hf/mrg/mysql-5.0-opt

into  mysql.com:/d2/hf/mrg/mysql-4.1-opt

into  mysql.com:/d2/hf/mrg/mysql-5.1-opt

into  whalegate.ndb.mysql.com:/home/tomas/mysql-5.0-ndb

into  whalegate.ndb.mysql.com:/home/tomas/mysql-5.1-single-user

into  xiphis.org:/home/antony/work2/mysql-5.1-engines.merge

  Move copying of global variables into thd.variables into plugin_thdvar_init().
  plugin_thdvar_init() may be called multiple times when THD::change_user() is called.
  This fixes a plugin ref-count leak when running the test mysql_client_test

into  moonbone.local:/mnt/gentoo64/work/27759-bug-5.0-opt-mysql

 fixed coverage of out-of-mem errors

 - added join cache indication in EXPLAIN (Extra column).
 - prefer filesort over full scan over 
   index for ORDER BY (because it's faster).
 - when switching from REF to RANGE because
   RANGE uses longer key turn off sort on
   the head table only as the resulting 
   RANGE access is a candidate for join cache
   and we don't want to disable it by sorting
   on the first table only. 

The LEAST/GREATEST functions compared DATE/DATETIME values as
strings which in some cases could lead to a wrong result.

A new member function called cmp_datetimes() is added to the
Item_func_min_max class. It compares arguments in DATETIME context
and returns index of the least/greatest argument.
The Item_func_min_max::fix_length_and_dec() function now detects when
arguments should be compared in DATETIME context and sets the newly
added flag compare_as_dates. It indicates that the cmp_datetimes() function
should be called to get a correct result.
Item_func_min_max::val_xxx() methods are corrected to call the
cmp_datetimes() function when needed.
Objects of the Item_splocal class now stores and reports correct original
field type.

into  magare.gmz:/home/kgeorge/mysql/work/B27531-5.1-opt-after-merge

Fix tests when InnoDB is not built-in. Innodb options would cause
mysqld to abort with an error indicating that the option is unknown.
Fix tests on Windows where mysql-test-run.pl was unable to probe
mysqld for version and variables information, caused by output
being redirected to a log file instead.

into  magare.gmz:/home/kgeorge/mysql/work/B27531-5.0-opt

When checking for applicability of join cache
we must disable its usage only if there is no
temp table in use.
When a temp table is used we can use join
cache (and it will not make the result-set 
unordered) to fill the temp table. The filesort() 
operation is then applied to the data in the temp 
table and hence is not affected by join cache
usage.
Fixed by narrowing the condition for disabling 
join cache to exclude the case where temp table
is used.