Initial import of WL#3726 "DDL locking for all metadata objects".

Backport of:
------------------------------------------------------------
revno: 2630.4.1
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Fri 2008-05-23 17:54:03 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  After review fixes in progress.
------------------------------------------------------------

This is the first patch in series. It transforms the metadata 
locking subsystem to use a dedicated module (mdl.h,cc). No 
significant changes in the locking protocol. 
The import passes the test suite with the exception of 
deprecated/removed 6.0 features, and MERGE tables. The latter
are subject to a fix by WL#4144.
Unfortunately, the original changeset comments got lost in a merge,
thus this import has its own (largely insufficient) comments.

This patch fixes Bug#25144 "replication / binlog with view breaks".
Warning: this patch introduces an incompatible change:
Under LOCK TABLES, it's no longer possible to FLUSH a table that 
was not locked for WRITE.
Under LOCK TABLES, it's no longer possible to DROP a table or
VIEW that was not locked for WRITE.

******
Backport of:
------------------------------------------------------------
revno: 2630.4.2
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 14:03:45 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  After review fixes in progress.

******
Backport of:
------------------------------------------------------------
revno: 2630.4.3
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 14:08:51 +0400
message:
  WL#3726 "DDL locking for all metadata objects"

  Fixed failing Windows builds by adding mdl.cc to the lists
  of files needed to build server/libmysqld on Windows.

******
Backport of:
------------------------------------------------------------
revno: 2630.4.4
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sat 2008-05-24 21:57:58 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  Fix for assert failures in kill.test which occured when one
  tried to kill ALTER TABLE statement on merge table while it
  was waiting in wait_while_table_is_used() for other connections
  to close this table.

  These assert failures stemmed from the fact that cleanup code
  in this case assumed that temporary table representing new
  version of table was open with adding to THD::temporary_tables
  list while code which were opening this temporary table wasn't
  always fulfilling this.

  This patch changes code that opens new version of table to
  always do this linking in. It also streamlines cleanup process
  for cases when error occurs while we have new version of table
  open.

******
WL#3726 "DDL locking for all metadata objects"
Add libmysqld/mdl.cc to .bzrignore.
******
Backport of:
------------------------------------------------------------
revno: 2630.4.6
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w
timestamp: Sun 2008-05-25 00:33:22 +0400
message:
  WL#3726 "DDL locking for all metadata objects".

  Addition to the fix of assert failures in kill.test caused by
  changes for this worklog.


Make sure we close the new table only once.

mysql-test/include/handler.inc

@@ -518,12 +518,15 @@ connect (flush,localhost,root,,);
 connection flush;
 --echo connection: flush
 --send flush tables;
-connection default;
---echo connection: default
+connect (waiter,localhost,root,,);
+connection waiter;
+--echo connection: waiter 
 let $wait_condition=
   select count(*) = 1 from information_schema.processlist
   where state = "Flushing tables";
 --source include/wait_condition.inc
+connection default;
+--echo connection: default
 handler t2 open;
 handler t2 read first;
 handler t1 read next;
@@ -550,12 +553,14 @@ connect (flush,localhost,root,,);
 connection flush;
 --echo connection: flush
 --send rename table t1 to t2;
-connection default;
---echo connection: default
+connection waiter;
+--echo connection: waiter 
 let $wait_condition=
   select count(*) = 1 from information_schema.processlist
   where state = "Waiting for table" and info = "rename table t1 to t2";
 --source include/wait_condition.inc
+connection default;
+--echo connection: default
 handler t2 open;
 handler t2 read first;
 --error ER_NO_SUCH_TABLE
@@ -566,7 +571,13 @@ connection flush;
 reap;
 connection default;
 drop table t2;
+connection flush;
 disconnect flush;
+--source include/wait_until_disconnected.inc
+connection waiter;
+disconnect waiter;
+--source include/wait_until_disconnected.inc
+connection default;
 
 #
 # Bug#30882 Dropping a temporary table inside a stored function may cause a server crash
@@ -699,19 +710,24 @@ handler t1 read a next;
 # Bug#41112: crash in mysql_ha_close_table/get_lock_data with alter table
 #
 
+connect(con1,localhost,root,,);
+connect(con2,localhost,root,,);
+
+connection default;
 --disable_warnings
 drop table if exists t1;
 --enable_warnings
 create table t1 (a int);
 insert into t1 values (1);
 handler t1 open;
-connect(con1,localhost,root,,);
+connection con1;
 send alter table t1 engine=memory;
-connection default;
+connection con2;
 let $wait_condition=
   select count(*) = 1 from information_schema.processlist
-  where state = "rename result table" and info = "alter table t1 engine=memory";
+  where state = "Waiting for table" and info = "alter table t1 engine=memory";
 --source include/wait_condition.inc
+connection default;
 --error ER_ILLEGAL_HA
 handler t1 read a next;
 handler t1 close;
@@ -720,6 +736,9 @@ connection con1;
 drop table t1;
 disconnect con1;
 --source include/wait_until_disconnected.inc
+connection con2;
+disconnect con2;
+--source include/wait_until_disconnected.inc
 connection default;
 
 #