Although the C standard mandates that sprintf return the number
of bytes written, some very ancient systems (i.e. SunOS 4)
returned a pointer to the buffer instead. Since these systems
are not supported anymore and are hopefully long dead by now,
simply remove the portability wrapper that dealt with this
discrepancy. The autoconf check was causing trouble with GCC.

Introduce a MySQL maintainer/developer mode that enables
a set of warning options for the C/C++ compiler. This mode
is intended to help improve the overall quality of the code.

The warning options are:

C_WARNINGS="-Wall -Wextra -Wunused -Wwrite-strings -Werror"
CXX_WARNINGS="$C_WARNINGS -Wno-unused-parameter"

Since -Wall is essentially a moving target, autoconf checks
are not run with warning options enabled, in particualr -Werror.
This decision might be revisited in the future. The patch also
fixes a mistake in the makefiles, where automake CXXFLAGS would
be set to CFLAGS.

The problem there is that HAVING condition evaluates const
parts of condition despite the condition has references
on aggregate functions. Table t1 became const tables
after make_join_statistics and table1.pk = 1, HAVING is
transformed into MAX(1) < 7 and taken away from HAVING.
The fix is to skip evaluation of HAVING conts parts if
HAVING condition has references on aggregate functions.

Fix the memory leak

Since the original fix for this bug lowercases the search pattern it's not a 
good idea to copy the search pattern to the output instead of the real table 
name found (since, depending on the case mode these two names may differ in 
case).
Fixed the infrmation_schema.test failure by making sure the actual table 
name of an inoformation schema table is passed instead of the lookup pattern
even when the pattern doesn't contain wildcards.

           due to GCC preprocessor change

Temporary workaround: disable abi_check if GCC >= 4.5

The atomic operations implementation on 5.1 has a few problems,
which might cause tests to abort randomly. Since no code in 5.1
uses atomic operations, simply remove the code.

Some test cases set ANSI_QUOTES in sql_mode.
So we have to use single quotes to quote literal strings.

DROP USER 
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENTbut, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave 
executes the log event, 'CURRENT_USER()' is expand to the user of slave 
SQL thread, but SQL thread's user name always NULL. This breaks the replication.

After this patch, session's user will be written into query log events 
if these statements call CURREN_USER() or 'ALTER EVENT' does not assign a definer.

class is mostly empty, initialize the base class explicitly in
the copy constructor.

If bzero is not available, resort to memset. Also, remove dead
bzero.c

Apart strict-aliasing warnings, fix the remaining warnings
generated by GCC 4.4.4 -Wall and -Wextra flags.

One major source of warnings was the in-house function my_bcmp
which (unconventionally) took pointers to unsigned characters
as the byte sequences to be compared. Since my_bcmp and bcmp
are deprecated functions whose only difference with memcmp is
the return value, every use of the function is replaced with
memcmp as the special return value wasn't actually being used
by any caller.

There were also various other warnings, mostly due to type
mismatches, missing return values, missing prototypes, dead
code (unreachable) and ignored return values.

Fixed an incomplete historical ALTER TABLE MODIFY trimming the trigger 
privilege bit from mysql.tables_priv.Table_priv column.
Removed the duplicate ALTER TABLE MODIFY.
Test suite added.

conflicts:
   conflict      include/my_alarm.h

POSIX requires that a signal handler defined with sigaction()
is not reset on delivering a signal unless SA_NODEFER or
SA_RESETHAND is set. It is therefore unnecessary to redefine
the handler on signal delivery on platforms where sigaction()
is used without those flags.

The problem is that QUICK_SELECT_DESC behaviour depends
on used_key_parts value which can be bigger than selected
best_key_parts value if an engine supports clustered key.
But used_key_parts is overwritten with best_key_parts
value that prevents from correct selection of index
access method. The fix is to preserve used_key_parts
value for further use in QUICK_SELECT_DESC.