and new binlog format called "mixed" (which is statement-based except if only row-based is correct,
in this cset it means if UDF or UUID is used; more cases could be added in later 5.1 release):
SET GLOBAL|SESSION BINLOG_FORMAT=row|statement|mixed|default;
the global default is statement unless cluster is enabled (then it's row) as in 5.1-alpha.
It's not possible to use SET on this variable if a session is currently in row-based mode and has open temporary tables (because CREATE
TEMPORARY TABLE was not binlogged so temp table is not known on slave),  or if NDB is enabled (because
NDB does not support such change on-the-fly, though it will later), of if in a stored function (see below).
The added tests test the possibility or impossibility to SET, their effects, and the mixed mode,
including in prepared statements and in stored procedures and functions.
Caveats:
a) The mixed mode will not work for stored functions: in mixed mode, a stored function will
always be binlogged as one call and in a statement-based way (e.g. INSERT VALUES(myfunc()) or SELECT myfunc()).
b) for the same reason, changing the thread's binlog format inside a stored function is
refused with an error message.
c) the same problems apply to triggers; implementing b) for triggers will be done later (will ask
Dmitri).
Additionally, as the binlog format is now changeable by each user for his session, I remove the implication
which was done at startup, where row-based automatically set log-bin-trust-routine-creators to 1
(not possible anymore as a user can now switch to stmt-based and do nasty things again), and automatically
set --innodb-locks-unsafe-for-binlog to 1 (was anyway theoretically incorrect as it disabled
phantom protection).
Plus fixes for compiler warnings.


mysql-test/r/rpl_row_4_bytes.result:
  update
mysql-test/t/rpl_row_4_bytes.test:
  don't influence next tests
sql/ha_archive.cc:
  please pay attention to this structure when you change it...
sql/ha_berkeley.cc:
  please pay attention to this structure when you change it...
sql/ha_blackhole.cc:
  please pay attention to this structure when you change it...
sql/ha_federated.cc:
  please pay attention to this structure when you change it...
sql/ha_heap.cc:
  please pay attention to this structure when you change it...
sql/ha_innodb.cc:
  please pay attention to this structure when you change it...
sql/ha_myisam.cc:
  please pay attention to this structure when you change it...
sql/ha_myisammrg.cc:
  please pay attention to this structure when you change it...
sql/ha_ndbcluster_binlog.cc:
  no more global 'binlog_row_based'
sql/ha_partition.cc:
  please pay attention to this structure when you change it...
sql/handler.cc:
  please pay attention to this structure when you change it...
sql/handler.h:
  it's good to initialize statically (to get no compiler warning) even if to a null value.
sql/item_func.cc:
  UDFs require row-based if this is the "mixed" binlog format.
sql/item_strfunc.cc:
  UUID() requires row-based binlogging if this is the "mixed" binlog format
sql/log.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/log.h:
  the enum enum_binlog_format moves to log.h from mysqld.cc as we need it in several places.
sql/log_event.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/log_event.h:
  this global variable not used anymore
sql/mysql_priv.h:
  these global variables not used anymore
sql/mysqld.cc:
  simplification in the handling of --binlog-format (but with no user-visible change), thanks to
  the new global system variable.
  RBR does not anymore turn on --log-bin-trust-function-creators and --innodb-locks-unsafe-for-binlog
  as these are global options and RBR is now settable per session.
sql/partition_info.cc:
  compiler warnings
sql/set_var.cc:
  new class of thread's variable, to handle the binlog_format (like sys_var_thd_enum except
  that is_readonly() is overriden for more checks before update).
  compiler warnings (ok'd by Serg)
sql/set_var.h:
  new class for the thread's binlog_format (see set_var.cc)
sql/share/errmsg.txt:
  some messages for when one can't toggle from one binlog format to another
sql/sp_head.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/sql_base.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/sql_class.cc:
  When a THD is initialized, we set its current_stmt_binlog_row_based
sql/sql_class.h:
  new THD::variables.binlog_format (the value of the session variable set by SET
  or inherited from the global value), and THD::current_stmt_binlog_row_based which tells if the
  current statement does row-based or statement-based binlogging. Both members are needed
  as the 2nd one cannot be derived only from the first one (the statement's type plays a role too),
  and the 1st one is needed to reset the 2nd one.
sql/sql_delete.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/sql_insert.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
sql/sql_load.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based.
sql/sql_parse.cc:
  when we are done with a statement, we reset the current_stmt_binlog_row_based to the value
  derived from THD::variables.binlog_format.
sql/sql_partition.cc:
  compiler warning
sql/sql_show.cc:
  compiler warning
sql/sql_table.cc:
  binlog_row_based -> thd->current_stmt_binlog_row_based
tests/mysql_client_test.c:
  compiler warning
mysql-test/r/ndb_binlog_basic2.result:
  new result
mysql-test/r/rpl_switch_stm_row_mixed.result:
  new result
mysql-test/t/ndb_binlog_basic2.test:
  new test to verify that if cluster is enabled, can't change binlog format on the fly.
mysql-test/t/rpl_switch_stm_row_mixed.test:
  test to see if one can switch between SBR, RBR, and "mixed" mode, and when one cannot,
  and test to see if the switching, and the mixed mode, work properly (using UUID() to test,
  as using UDFs is not possible in the testsuite for portability reasons).