Fixed reference to not initialized memory detected by valgrind

sql/sql_select.cc:
  A bit better fix for tmp-table problem:
  Use only dynamic_record format for group by and distinct.
storage/maria/ma_create.c:
  DYNAMIC_RECORD format doesn't pack VARCHAR fields.
  This change fixes a non-fatal uninitialized memory copy.

The reason for this is that BLOCK_RECORD format is not good when there is a lot of duplicated keys as it first writes the data (to get the row position) and
then writes the key (and thus checks for duplicates).

Fixed problem that global status variables 'bytes_recieved' and 'binlog_bytes_written' where not correctly updated 

Fixed crash when setting query_cache_type to 0.

client/Makefile.am:
  Added zlib include (needed by checksum.c)
sql/set_var.cc:
  Updated call to disable_query_cache()
sql/sql_cache.cc:
  Don't give warning if we start mysqld with --query_cache_type=0 --query_cache-size=0
  Fixed crash when setting query_cache_type to 0 (we shouldn't call query_cache.disable_query_cache() when there is no current_thd)
sql/sql_cache.h:
  Added THD to disable_query_cache()

strings/ctype-simple.c:
  Fixed some compiler warnings

After talking to HeidiSQL people -  libmysql.dll that comes with their distribution in place, dont replace with our own.
It also will result in less HeidiSQL restarts during MariaDB upgrades (since libmysql.dll won't be replaced)

VS did not like to execute 2 commands in custom build step, workaround is 
to use single COMMAND instead of 2.

Upgraded to latest handlersocket code. This fixed LP:766870  "Assertion `next_insert_id == 0' failed with handlersocket"

sql/handler.cc:
  Added DBUG_ code

sql/mysql_priv.h:
  Make opt_help global
sql/mysqld.cc:
  Don't give (double) warnings about lower case file systems if --help is given.
  Don't give warning about non existing data directory if --help is given.
sql/sql_plugin.cc:
  Give a better warning if --help is used and plugin table doesn't exists

The code that added semi-join transformations missed checking
the state of the fixed flag for the items built with the
and_items function before calls of the fix_fields method.
This could lead to an abort failure when the first argument
of and_items() happened to be NULL.
 

Strict mode now gives error if one tries to update a virtual column.

mysql-test/suite/vcol/r/vcol_column_def_options_innodb.result:
  Updated test results
mysql-test/suite/vcol/r/vcol_column_def_options_myisam.result:
  Updated test results
mysql-test/suite/vcol/r/vcol_keys_innodb.result:
  Updated test results
mysql-test/suite/vcol/r/vcol_keys_myisam.result:
  Updated test results
mysql-test/suite/vcol/r/vcol_misc.result:
  Added new test for 'show columns' and error handling when trying to update a virtual column.
mysql-test/suite/vcol/t/vcol_misc.test:
  Added new test for 'show columns' and error handling when trying to update a virtual column.
sql/sql_base.cc:
  Strict mode now gives error if one tries to update a virtual column.
sql/sql_show.cc:
  Show PERSISTENT instead of VIRTUAL for persistent columns.

Fixed lock sorting and lock check issues with thr_lock that caused warnings when running test suite.
Safety check that could cause core dump when doing create table with virtual column.

mysql-test/mysql-test-run.pl:
  Show also warnings from thr_lock (which starts with just Warning, not Warning:)
mysql-test/r/lock.result:
  Added test that showed not relevant warning when using table locks.
mysql-test/t/lock.test:
  Added test that showed not relevant warning when using table locks.
mysys/thr_lock.c:
  Fixed sorting of locks.
  (Old sort code didn't handle case where TL_WRITE_CONCURRENT_INSERT must be sorted before TL_WRITE)
  Added more information to check_locks warning output.
  Fixed wrong testing of multiple different write locks for same table.
sql/item_cmpfunc.cc:
  Safety check that could cause core dump when doing create table with virtual column.

- make sp.test work both with and without query_cache (attempt 2)
- fix compile warning in make_sort_key(), as directed by SergeiG

to be optimizer_switch flags mrr=on|off and mrr_cost_based=on|off.

- Don't attempt to construct FirstMatch access method if we've 
  just figured three lines above that it can't be used (because join
  prefix doesn't have the needed tables), and so have set 
    pos->first_firstmatch_table= MAX_TABLES 
  Attempts to analyze join->positions[MAX_TABLES] caused valgrind warnings

Added HeidiSQL as example, i.e cmake -DWITH_THIRD_PARTY=HeidiSQL  
and building MSI will bundle HeidiSQL.

Corrected the code from the patch for  LP bug 702322.

There is a potential race when we stop the slave. It may take some time for
the master to detect that the slave connection is closed (eg. if scheduling
delays the TCP RSET packet or whatever). Since we inject only a single corrupt
binlog event, we may be unfortunate enough to inject it on the wrong
connection, to a slave io thread that's already stopped.

Fix by waiting for the old dump thread on the master to go away before
injecting the corrupt event.

- Remove garbage comments

introduced at the latest merge 5.1->5.2->5.3.
It is basically not needed since if SQL_SELECT::pre_idx_push_select_cond 
is not NULL then SQL_SELECT::original_cond would point to the same condition
as SQL_SELECT::pre_idx_push_select_cond. Otherwise SQL_SELECT::original_cond
would be equal to SQL_SELECT::cond.