Needed for substitution in some tests.

with gcc 4.3.2
      
Compiling MySQL with gcc 4.3.2 and later produces a number of 
warnings, many of which are new with the recent compiler
versions.
      
This bug will be resolved in more than one patch to limit the
size of changesets. This is the first patch, fixing a number 
of the warnings, predominantly "suggest using parentheses 
around && in ||", and empty for and while bodies.

This variable is defined by default and one should not do it
directly as the socket variable is not available on Windows.

the --big-test flag is supplied. Test is too resource intensive
under normal valgrind runs (takes more than 30min on powerful
hardware).

with gcc 4.3.2

Compiling MySQL with gcc 4.3.2 and later produces a number of 
warnings, many of which are new with the recent compiler
versions.

This bug will be resolved in more than one patch to limit the
size of changesets. This is the first patch, fixing a number 
of the warnings, predominantly "suggest using parentheses 
around && in ||", and empty for and while bodies.

Under a debug run, the trace file grows to a few gigabytes.
Under valgrind, takes more then 20 minutes due to the high
number of insert statements.

variable. The problem was that THD::connect_utime could be
used without being initialized when the main thread is used
to handle connections (--thread-handling=no-threads).

Under a debug run, the trace file grows to a few gigabytes.
Under valgrind, takes more then 20 minutes due to the high
number of insert statements.

            uninitialized variable used as subscript

Grouping select from a "constant" InnoDB table (a table
of a single row) joined with other tables caused a crash.

use same (slightly unwieldy) name in all trees; fix before this version goes "public".
bless ctype to avoid upmerge conflict, le sigh.

The problem is that when a optimization of read-only transactions
(bypass 2-phase commit) was implemented, it removed the code that
reseted the XID once a transaction wasn't active anymore:

sql/sql_parse.cc:

-  bzero(&thd->transaction.stmt, sizeof(thd->transaction.stmt));
-  if (!thd->active_transaction())
-    thd->transaction.xid_state.xid.null();
+  thd->transaction.stmt.reset();

This mostly worked fine as the transaction commit and rollback
functions (in handler.cc) reset the XID once the transaction is
ended. But those functions wouldn't reset the XID in case of
a empty transaction, leading to a assertion when a new starting
a new XA transaction.

The solution is to ensure that the XID state is reset when empty
transactions are ended (by either commit or rollback). This is
achieved by reorganizing the code so that the transaction cleanup
routine is invoked whenever a transaction is ended.

a binary distribution of the server as the MTR valgrind option
relies on it to silence unmeaningful warnings.

Implemented a way to circumvent the always true comparison by
having nested macros (as suggested on review).

Merged the 5.0 fix to 5.1 and fixed the 5.1 specific warnings.

Fixed the 5.0-bugteam MacOSX warnings.

 - Rename the  functions in mysqld that conflict with the one in the
   external interface defined by mysql.h

Holding on to the temporary inno hash index latch is an optimization in
many cases, but a pessimization in some others.

Release temporary latches for those corner cases we (or rather, or customers,
thanks!) have identified, that is, when we are about to do something that
might take a really long time, like REPAIR or filesort.