Item_func_spatial_collection::val_str
        
When the concatenation function for geometry data collections
reads the binary data it was not rigorous in checking that there
is data available, leading to invalid reads and crashes.
Fixed by making checking stricter.

This patch corrects a misstake in the test case for bug patch 43658.

There was a race in the test case when the thread id was retrieved from the processlist.
The result was that the same thread id was signalled twice and one thread id wasn't
signalled at all.

The affected platforms appears to be limited to linux.

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 second patch, fixing more
of the warnings.

to a test file that guarantees the presence of partition code

Early patch submitted for discussion.

It is possible for more than one thread to enter the condition
in query_cache_insert(), but the condition predicate is to
signal one thread each time the cache status changes between
the following states: {NO_FLUSH_IN_PROGRESS,FLUSH_IN_PROGRESS,
TABLE_FLUSH_IN_PROGRESS}

Consider three threads THD1, THD2, THD3

   THD2: select ... => Got a writer in ::store_query
   THD3: select ... => Got a writer in ::store_query
   THD1: flush tables => qc status= FLUSH_IN_PROGRESS;
                      new writers are blocked.
   THD2: select ... => Still got a writer and enters cond in
                       query_cache_insert
   THD3: select ... => Still got a writer and enters cond in
                       query_cache_insert
   THD1: flush tables => finished and signal status change.
   THD2: select ... => Wakes up and completes the insert.
   THD3: select ... => Happily waiting for better times. Why hurry?

This patch is a refactoring of this lock system. It introduces four new methods:
   Query_cache::try_lock()
   Query_cache::lock()
   Query_cache::lock_and_suspend()
   Query_cache::unlock()

This change also deprecates wait_while_table_flush_is_in_progress(). All threads are
queued and put on a conditional wait. On each unlock the queue is signalled. This resolve
the issues with left over threads. To assure that no threads are spending unnecessary
time waiting a signal broadcast is issued every time a lock is taken before a full
cache flush.

times (ie: 2:16:20).

statements missed from general log

A FLUSH LOGS is added to ensure that the log info hits
the file before attempting to process.

crashes server!

The problem affects the scenario when index merge is followed by a filesort
and the sort buffer is not big enough for all the sort keys.
In this case the filesort function will read the data to the end through the 
index merge quick access method (and thus closing the cursor etc), 
but will leave the pointer to the quick select method in place.
It will then create a temporary file to hold the results of the filesort and
will add it as a sort output file (in sort.io_cache).
Note that filesort will copy the original 'sort' structure in an automatic
variable and restore it after it's done.
As a result at exiting filesort() we have a sort.io_cache filled in and 
nothing else (as a result of close of the cursors at end of reading data 
through index merge).
Now create_sort_index() will note that there is a select and will clean it up
(as it's been used already by filesort() reading the data in). While doing that
a special case in the index merge destructor will clean up the sort.io_cache,
assuming it's an output of the index merge method and is not needed anymore.
As a result the code that tries to read the data back from the filesort output 
will get no data in both memory and disk and will crash.
      
Fixed similarly to how filesort() does it : by copying the sort.io_cache structure
to a local variable, removing the pointer to the io_cache (so that it's not freed 
by QUICK_INDEX_MERGE_SELECT::~QUICK_INDEX_MERGE_SELECT) and restoring the original 
structure (together with the valid pointer) after the cleanup is done.
This is a safe thing to do because all the structures are already cleaned up by
hitting the end of the index merge's read method (QUICK_INDEX_MERGE_SELECT::get_next()) 
and the cleanup code being written in a way that tolerates repeating cleanups.

The SQL-mode PAD_CHAR_TO_FULL_LENGTH could prevent a DROP USER
statement from privileges associated with the user being dropped.
What ocurred was that reading from the User and Host fields of
the tables tables_priv or columns_priv would yield values padded
with spaces, causing a failure to match a specified user or host 
('user' != 'user     ');

The solution is to disregard the PAD_CHAR_TO_FULL_LENGTH mode
when iterating over and matching values in the privileges tables
for a DROP USER statement.

statements missed from general log

A refinement of the test in the previous patch to avoid
using sleep as a means to ensure that timestamps are
added to the log entries.