Adding comments to some of the high-level functions in replication.

sql/log_event.h:
  Fixed some mistakes in comments.
sql/repl_failsafe.cc:
  Added comment for show_slave_hosts()
sql/slave.cc:
  Added comment for show_master_info(), handle_slave_[sql|io](), and next_event()
sql/sql_binlog.cc:
  Added @param comment.
sql/sql_lex.h:
  Added comment for st_lex_master_info.
sql/sql_repl.cc:
  Added comments for functions executing a statement:
      PURGE BINARY LOGS
      START SLAVE
      STOP SLAVE
      RESET SLAVE
      CHANGE MASTER
      RESET MASTER
      SHOW BINLOG EVENTS
      SHOW MASTER STATUS
      SHOW BINARY LOGS

The special TRUNCATE TABLE (DDL) transaction wasn't being properly
rolled back if a error occurred during row by row deletion. The
error can be caused by a foreign key restriction imposed by InnoDB
SE and would cause the server to erroneously issue a implicit
commit.

The solution is to rollback the transaction if a truncation via row
by row deletion fails, otherwise commit. All effects of a TRUNCATE 
ABLE operation are rolled back if a row by row deletion fails.

mysql-test/include/commit.inc:
  Truncate always starts a transaction and commits at the end.
  The commit at the end increases the count by two, one is the
  storage engine commit and the other is the binary log.
mysql-test/r/commit_1innodb.result:
  Update test case results.
mysql-test/r/innodb_mysql.result:
  Update test case results.
mysql-test/t/innodb_mysql.test:
  Add test case for Bug#37016
sql/sql_delete.cc:
  Move truncation using row by row deletion to its own function.
  If row by row deletion fails, rollback the transaction.
  
  Remove the meddling with disabling and enabling of autocommit
  as TRUNCATE transaction is now explicitly ended (committed
  or rolled back).

Problem: when the server reads a log_event from file, it should read
the post-header lengths from the format_description_log_event. Some
event types which currently have post-header length 0 did not do this,
and instead had a hard-coded zero length for the post-header. That
means the current server version will not be able to read future
versions of these events.
Fix: make the reader functions read the post-header.


sql/log_event.cc:
   - Made Format_description_log_event constructor initialize all
     post-header lengths explicitly, to make it easier to find them
     in the source code.
   - After this, it is no longer necessary to pass the MY_ZEROFILL
     flag to my_malloc. I removed the flag and added a sanity-check
     that will be executed only in debug-mode.
   - Made INTVAR, RAND, USER_VAR, and XID events skip post_header_len
     when reading from file.
sql/log_event.h:
  Added explicit defines for the lengths of all event types.

The binlog_innodb test was sensitive to what tests ran before it.  Now run
FLUSH STATUS before performing operations that need to be checked.

sys_var_thd_ulong::update() was improperly casting an option value from
ulonglong to ulong before comparing it to the max allowed value.  On systems
where ulong and ulonglong are of different size, this caused values greater
than ULONG_MAX to wrap around (not be truncated to ULONG_MAX, which appears to
have been the intention of the original coder), and caused some checks to work
incorrectly.  This wasn't generally visible to the user, because later checks
would prevent the wrapped-around value from being used.  But it caused warning
messages to differ between 32- and 64-bit platforms.  Fix is to just remove the
cast.  Also added a DBUG_ASSERT to ensure that the value really is capped
properly before finally stuffing it into the ulong.

           locking type of temp table

The problem is that INSERT INTO .. SELECT FROM .. and CREATE
TABLE .. SELECT FROM a temporary table could inadvertently
overwrite the locking type of the temporary table. The lock
type of temporary tables should be a write lock by default.

The solution is to reset the lock type of temporary tables
back to its default value after they are used in a statement.

mysql-test/r/innodb_mysql.result:
  Add test case result for Bug#41348
mysql-test/r/temp_table.result:
  Add test case result for Bug#41348
mysql-test/t/innodb_mysql.test:
  Add test case for Bug#41348
mysql-test/t/temp_table.test:
  Add test case for Bug#41348
sql/sql_base.cc:
  Allow the lock type of temp tables to be overwritten now that
  the the value is being restored once the table is marked as
  free for re-use. This makes the behavior consistent with that
  of non-temporary tables and avoids confusion.

Added function to check for diff and return an error message if the utility is not present.
Previously, the way we did this didn't work on Windows, but did work on *Nix systems.

case.

Execution of queries containing the CASE function of
aggregate function like in "SELECT ... CASE ARGV(...) WHEN ..."
crashed the server.


The CASE function caches pointers to concrete comparison
functions for an each pair of types of CASE-WHERE clause
parameters, i.e. for the "CASE INT_RESULT WHERE REAL_RESULT
THEN ... WHERE DECIMAL_RESULT ... END" function call it
caches comparisons for INT_RESULT with REAL_RESULT and
for INT_RESULT with DECIMAL_RESULT. Usually a result
type is known after a call to the fix_fields function,
however, the setup_copy_fields function call may
wrap aggregate items with Item_copy_string that has
STRING_RESULT result type, so setup_copy_fields may
change argument result types of the CASE function after
call to Item_func_case::fix_fields/fix_length_and_dec.
Then the Item_func_case::find_item function tries to
use comparison function for unexpected pair of the
STRING_RESULT and some other type - that caused
an assertion failure of server crash.

The Item_func_case::fix_length_and_dec function has
been modified to take into account possible STRING_RESULT
result type in the presence of aggregate arguments of
the CASE function.


mysql-test/r/func_in.result:
  Added test case for bug #41363.
mysql-test/t/func_in.test:
  Added test case for bug #41363.
sql/item_cmpfunc.cc:
  Bug #41363: crash of mysqld on windows with aggregate in case
  
  The Item_func_case::fix_length_and_dec function has
  been modified to take into account possible STRING_RESULT
  result type in the presence of aggregate arguments of
  the CASE function.

Disabled rpl_binlog_corruption since it requires the new mtr,
which only exists in 5.1-rpl / 6.0-rpl.
Please re-enable the test in 5.1-rpl / 6.0-rpl.


mysql-test/suite/rpl/t/disabled.def:
  Disabled rpl_binlog_corruption since it requires the new mtr,
  which only exists in 5.1-rpl / 6.0-rpl.

Problem: When an Incident_log_event contains a bad incident number on disk,
the server crashes with an assertion.
Fix: Don't validate input with assertions. Use errors.

mysql-test/include/cleanup_fake_relay_log.inc:
  Added auxiliary file to restore things that setup_fake_relay_log.inc did.
mysql-test/include/setup_fake_relay_log.inc:
  Added auxiliary file to setup replication from an existing relay log.
mysql-test/std_data/bug40482-bin.000001:
  Binlog file for rpl.rpl_binlog_corruption
mysql-test/suite/rpl/t/rpl_binlog_corruption.test:
  New test file.
sql/log_event.cc:
  Check that the incident number is correct at the time the event is constructed.
  Do not assert it at the time it is printed.
sql/log_event.h:
  Incident_log_event::is_valid() should verify that the incident number is valid.
sql/rpl_constants.h:
  Incident numbers should be hard-coded, since they may appear in files.

The problem: data file can not be deleted on win because
there is another opened instance of this file.
Data file might be opened twice, on table opening stage and
during write_row execution. We need to close both instances
to satisfy Win.


mysql-test/r/csv.result:
  test result
mysql-test/t/csv.test:
  test case
storage/csv/ha_tina.cc:
  The problem: data file can not be deleted on win because
  there is another opened instance of this file.
  Data file might be opened twice, on table opening stage and
  during write_row execution. We need to close both instances
  to satisfy Win.

Added global status variable 'Queries' which represents
total amount of queries executed by server including
statements executed by SPs.
note: It's old behaviour of 'Questions' variable.


mysql-test/r/status.result:
  test result
mysql-test/t/status.test:
  test case
sql/mysqld.cc:
  Added global status variable 'Queries' which represents
  total amount of queries executed by server including
  statements executed by SPs.
  note: It's old behaviour of 'Questions' variable.
sql/sql_show.cc:
  Added global status variable 'Queries' which represents
  total amount of queries executed by server including
  statements executed by SPs.
  note: It's old behaviour of 'Questions' variable.
sql/structs.h:
  Added global status variable 'Queries' which represents
  total amount of queries executed by server including
  statements executed by SPs.
  note: It's old behaviour of 'Questions' variable.

Problem was an errornous date that lead to end partition
was before the start, leading to a crash.

Solution was to check greater or equal instead of only
equal between start and end partition.

NOTE: partitioning pruning handles incorrect dates
differently than index lookup, which can give different
results in a partitioned table versus a non partitioned
table for queries having 'bad' dates in the where clause.

mysql-test/r/partition_pruning.result:
  Bug#40972: some sql execution lead the whole databse crashing
  
  Updated result file
mysql-test/t/partition_pruning.test:
  Bug#40972: some sql execution lead the whole databse crashing
  
  Added test.
sql/sql_partition.cc:
  Bug#40972: some sql execution lead the whole databse crashing
  
  There can be cases where the start/cur partition is greater
  than the end partition, so it must not continue, since that
  can lead to a crash.

Table could be marked dependent because it is
either 1) an inner table of an outer join, or 2) it is a part of
STRAIGHT_JOIN. In case of STRAIGHT_JOIN table->maybe_null should not
be assigned. The fix is to set st_table::maybe_null to 'true' only
for those tables which are used in outer join.



mysql-test/r/select.result:
  test result
mysql-test/t/select.test:
  test case
sql/sql_select.cc:
  Table could be marked dependent because it is
  either 1) an inner table of an outer join, or 2) it is a part of
  STRAIGHT_JOIN. In case of STRAIGHT_JOIN table->maybe_null should not
  be assigned. The fix is to set st_table::maybe_null to 'true' only
  for those tables which are used in outer join.
sql/sql_select.h:
  added comment