Problem: The functions my_like_range_xxx() returned
badly formed maximum strings for Asian character sets,
which made problems for storage engines.

Fix: 
- Removed a number my_like_range_xxx() implementations,
  which were in fact dumplicate code pieces.
- Using generic my_like_range_mb() instead.
- Setting max_sort_char member properly for Asian character sets
- Adding unittest/strings/strings-t.c, 
  to test that my_like_range_xxx() return well-formed 
  min and max strings.

Notes:

- No additional tests in mysql/t/ available.
  Old tests cover the affected code well enough.

Do not attempt to test the innodb plugin with the embedded server,
it's not supported for now.

Bug#49542 - Do as the comment suggests and downgrade directory errors from find_file() to a warning unless they happen during a SHOW command.

SHOW DATABASES LIKE ... was not converting to lowercase on comparison as the
documentation is suggesting. 
Fixed it to behave similarly to SHOW TABLES LIKE ... and updated the failing
on MacOSX lowercase_table2 test case.

to write into a closed socket

           due to GCC preprocessor change
      
Addendum for trunk: add -DMYSQL_ABI_CHECK to the cmake ABI check.

           due to GCC preprocessor change

Addendum for trunk: do not include system header when checking
the ABI.

Fix warnings flagged by the new warning option -Wunused-but-set-variable
that was added to GCC 4.6 and that is enabled by -Wunused and -Wall. The
option causes a warning whenever a local variable is assigned to but is
later unused. It also warns about meaningless pointer dereferences.

           due to GCC preprocessor change
      
The problem is that newer GCC versions treats missing headers
as fatal errors. The solution is to use a guard macro to prevent
the inclusion of system headers when checking the ABI with the
C Preprocessor.

Reference: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15638
           http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44836

           table with active trx

Essentially, the problem is that InnoDB does a implicit commit
when a cursor (table handler) is unlocked/closed, creating
a dissonance between the transaction state within the server
layer and the storage engine layer. Theoretically, a statement
transaction can encompass several table instances in a similar
manner to a multiple statement transaction, hence it does not
make sense to limit a statement transaction to the lifetime of
the table instances (cursors) used within it.

Since this particular instance of the problem is only triggerable
on 5.1 and is masked on 5.5 due 2PC being skipped (assertion is in
the prepare phase of a 2PC), the solution (which is less risky) is
to explicitly end the transaction before the cached table is unlock
on rename table.

The patch is to be null merged into trunk.

Problem: when SHOW BINLOG EVENTS was issued, it increased the value of
@@session.max_allowed_packet. This allowed a non-root user to increase
the amount of memory used by her thread arbitrarily. Thus, it removes
the bound on the amount of system resources used by a client, so it
presents a security risk (DoS attack).

Fix: it is correct to increase the value of @@session.max_allowed_packet
while executing SHOW BINLOG EVENTS (see BUG 30435). However, the
increase should only be temporary. Thus, the fix is to restore the value
when SHOW BINLOG EVENTS ends.
The value of @@session.max_allowed_packet is also increased in
mysql_binlog_send (i.e., the binlog dump thread). It is not clear if this
can cause any trouble, since normally the client that issues
COM_BINLOG_DUMP will not issue any other commands that would be affected
by the increased value of @@session.max_allowed_packet. However, we
restore the value just in case.