This patch implements the idea of the bug report by making Event_queue
unaware of Event_db_repository by making a higher level class - Events,
which is aware of most of all classes, responsible for passing all data
needed for adding/updating/deleting an event to/from the queue.

Introduces few new classes :
 - Event_worker_thread
 - Event_queue_element_for_exec

into  moonlight.home:/home/tomash/src/mysql_ab/mysql-5.1-bug23527

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

into  moonlight.home:/home/tomash/src/mysql_ab/mysql-5.1-bug23527

           high load

MySQL server could crash if two or more threads would initiate query
cache resize at the moments very close in time.

The problem was introduced with the fix of bug 21051 in 5.0 and 5.1:
simultaneous query cache resizes would wait for the first one in
progress, but then each thread would try to finish the operation,
accessing the data that was already reset (attempt to dereference
'bins' pointer, which may be NULL already).

The solution is to check after synchronization if another thread has
done the reset already (test 'query_cache_size > 0' again).

No test case is provided because the bug is a subject to a race.

  Don't use -Wshadow by default yet

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

into  bk-internal.mysql.com:/data0/bk/mysql-5.1-marvel

into  bk-internal.mysql.com:/data0/bk/mysql-5.1-marvel

into  poseidon.mysql.com:/home/tomas/mysql-5.1-new-ndb

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

into  poseidon.mysql.com:/home/tomas/mysql-5.1-new-ndb

- added extra cluster connect inicator bit for better handeling of delacation of event operations on cluster disconnect
- added extra assert to try to track down valgrind issue

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

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

into  weblab.(none):/home/marcsql/TREE/mysql-5.1-21029

The build scripts in general, using automake, autoconf, etc, contain several
special commands and work around all related to the way the bison code in the
parser is built, for sql/sql_yacc.yy. These work arounds, accumulated over
time during development, ultimately cause the build scripts to be unstable
and cause build defects by not enforcing dependencies.

This fix simplifies the build process and aligns it with the automake tooling,
which provides native support for bison and *.yy files.

In particular, the following problem have been fixed:
- dependencies with sql_yacc.cc were not honored (Bug 21029), leading to
  corrupted builds,
- the work around introduced by Bug 24557, to cleanup the generated files
  sql_yacc.h and sql_yacc.cc, has been removed,
- the generated makefile, in a source distribution, used to destroy the files
  sql_yacc.h and sql_yacc.cc on a 'make clean' target. This has been fixed:
  these files are now removed by make maintainer-clean.
- The root cause of the problem found with gcc 4.1 (see Bug 24619) has been
  clearly documented, and the "sed" hack has been replaced by a cleaner
  work around, when building the code with bison 1.875.
- Removed the file sql/sql_yacc.yy.bak, added by WL 3031 by accident.
- Removed the unnecessary AM_YFLAG= --debug introduced by WL 3432, since
  the compiling option DBUG_OFF takes precedence when setting YYDEBUG.

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

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

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

the team tree for additional investigation.

into  mockturtle.local:/home/dlenev/src/mysql-5.0-merge

into  mockturtle.local:/home/dlenev/src/mysql-5.1-merge

into  chilla.local:/home/mydev/mysql-5.0-bug24607

into  chilla.local:/home/mydev/mysql-5.1-bug24607

into  chilla.local:/home/mydev/mysql-5.1-bug24607

After merge fix

into  chilla.local:/home/mydev/mysql-5.0-bug24607

Fixed test. On 32-bit machines which compile without
-DBIG_TABLES, MAX_ROWS is truncated to a 32-bit value.
Using a value below 4G is portable.

into  kahlann.erinye.com:/home/df/mysql/build/mysql-5.0-build-work

into  kahlann.erinye.com:/home/df/mysql/build/mysql-5.1-build-work

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.1-engines

table in insert ... on duplicate key" in 5.1 tree.

into  mockturtle.local:/home/dlenev/src/mysql-5.1-bg24491

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.0-engines