ALTER TABLE on a MERGE table could cause a deadlock with two
other connections if we reached a situation where:

1) A connection doing ALTER TABLE can't upgrade to MDL_EXCLUSIVE on the
parent table, but holds TL_READ_NO_INSERT on the child tables.
2) A connection doing DELETE on a child table can't get TL_WRITE on it
since ALTER TABLE holds TL_READ_NO_INSERT.
3) A connection doing SELECT on the parent table can't get TL_READ on 
the child tables since TL_WRITE is ahead in the lock queue, but holds
MDL_SHARED_READ on the parent table preventing ALTER TABLE from upgrading.

For regular tables, this deadlock is avoided by having ALTER TABLE
take a MDL_SHARED_NO_WRITE metadata lock on the table. This prevents
DELETE from acquiring MDL_SHARED_WRITE on the table before ALTER TABLE
tries to upgrade to MDL_EXCLUSIVE. In the example above, SELECT would
therefore not be blocked by the pending DELETE as DELETE would not be
able to enter TL_WRITE in the table lock queue.

This patch fixes the problem for merge tables by using the same metadata
lock type for child tables as for the parent table. The child tables will
in this case therefore be locked with MDL_SHARED_NO_WRITE, preventing
DELETE from acquiring a metadata lock and enter into the table lock queue.

Change in behavior: By taking the same metadata lock for child tables
as for the parent table, LOCK TABLE on the parent table will now also
implicitly lock the child tables. Since LOCK TABLE on the parent table
now takes more than one metadata lock, it is possible for LOCK TABLE
... WRITE on the parent table or child tables to give ER_LOCK_DEADLOCK
error.

Test case added to mdl_sync.test.
Merge.test/.result has been updated to reflect the change to LOCK TABLE.

 create data dir correctly in initial_database target on Windows
 handle case where INSTALL_MYSQLTESTDIR is empty (e.g someone does not want
 to install tests)

Merge cleanup, fixed a build warning:

my_getopt.c:156: warning: 'opt_found' may be used uninitialized in this function

       made libmysqld/Makefile.am to have same licence as libmysqld/CMakeLists.txt

per-file comments:
  libmysqld/Makefile.am
Bug#54906      Inconsistent license of libmysqld
        Added GPL license header instead of Library GPL.

Problem:
- ORDER BY for utf8mb4_bin, utf16_bin and utf32_bin returned
  results in a wrong order, because old functions
  (supporting only BMP range) were used to handle these collations.
- Additionally, utf16_bin did not sort supplementary characters
  between U+D700 and U+E000, as WL#1213 specification specified.

to allow temp table operations) -- prerequisite patch #3.

Rename open_temporary_table() to open_table_uncached().
open_temporary_table() will be introduced in following patches
to open temporary tables for a statement.

check_merge_table_access() used to do two things:
  - set proper database for every merge table child;
  - check SELECT | UPDATE | DELETE for merge table children.

Setting database is not needed anymore, since it's done
on the parsing stage.

Thus, check_merge_table_access() can be removed;
needed privileges can be checked using check_table_access().

This allows to avoid mixing it up with pointer to TABLE object
which will be introduced to this function in one of upcoming
patches.

It was added by mistake during backport from 6.0.

to allow temp table operations) -- prerequisite patch #2.

Introduce a new form of find_temporary_table() function:
find_temporary_table() by a table key. It will be used
in further patches.

Replace find_temporary_table(table_list->db, table_list->name)
by more appropiate find_temporary_table(table_list) across
the codebase.

from 5.1.50 to 5.5.6".

Debug builds of the server aborted due to an assertion
failure when DROP DATABASE statement was run on an
installation which had outdated or corrupt mysql.proc table.
Particularly this affected the mysql_upgrade tool which is
run as part of 5.1 to 5.5 upgrade.

The problem was that sp_drop_db_routines(), which was invoked
during dropping of the database, could have returned without
closing and unlocking mysql.proc table in cases when this
table was not up-to-date with the current server. As a result
further attempt to open and lock the mysql.event table, which
was necessary to complete dropping of the database, ended up
with an assert.

This patch solves this problem by ensuring that
sp_drop_db_routines() always closes mysql.proc table and
releases metadata locks on it. This is achieved by changing
open_proc_table_for_update() function to close tables and
release metadata locks acquired by it in case of failure.
This step also makes behavior of the latter function
consistent with behavior of open_proc_table_for_read()/
open_and_lock_tables().


Test case for this bug was added to sp-destruct.test.

            "Access compatibility" syntax

The "wild" "DELETE FROM table_name.* ... USING ..." syntax
for multi-table DELETE statements is documented but it was
lost in the fix for the bug 30234.

The table_ident_opt_wild parser rule has been added
to restore the lost syntax.

 - Remove include of ha_ndbcluster_tables.h from mysqldump.c

so test case has to be updated.

      
The lock_type is upgrade to TL_WRITE from TL_WRITE_DELAYED for
INSERT DELAYED when inserting multi values in one statement.
It's safe. But it causes an unsafe warning in SBR.
      
Make INSERT DELAYED safe by logging it as INSERT without DELAYED.

            == MYSQL_TYPE_LONGLONG

A MIN/MAX() function with a subquery as its argument could lead
to a debug assertion on debug builds or wrong data on release
ones.

The problem was a combination of the following factors:

- Item_sum_hybrid::fix_fields() might use the argument
(args[0]) to calculate 'hybrid_field_type' which was later used
to decide how the data should be sent to the client.

- Item_sum::make_field() might use the argument again to
calculate the field's type when sending result set metadata to
the client.

- The argument could be changed in between these two calls via
  Item::set_arg() leading to inconsistent metadata being
  reported.

Here is what was happening for the bug's test case:

1. Item_sum_hybrid::fix_fields() calculates hybrid_field_type
as MYSQL_TYPE_LONGLONG based on args[0] which is an
Item::SUBSELECT_ITEM at that time.

2. A temporary table is created to execute the
query. create_tmp_field_from_item() creates a Field_long object
according to the subselect's max_length.

3. The subselect item in Item_sum_hybrid is replaced by the
Item_field object referencing the newly created Field_long.

4. Item_sum::make_field() rightfully returns the
MYSQL_TYPE_LONG type when calculating the result set metadata.

5. When sending the actual data, Item::send() relies on the
virtual field_type() function which in our case returns
previously calculated hybrid_field_type == MYSQL_TYPE_LONGLONG.

It looks like the only solution is to never refer to the
argument's metadata after the result metadata has been
calculated in fix_fields(), since the argument itself may be
different by then. In this sense, Item_sum::make_field() should
never be used, because it may rely on the argument's metadata
and is only called after fix_fields(). The "default"
implementation in Item::make_field() should be used instead as
it relies only on field_type(), but not on the argument's type.

Fixed by removing Item_sum::make_field() so that the superclass
implementation Item::make_field() is always used.

to allow temp table operations) -- prerequisite patch #1.
  
Move a piece of code that initialiazes TABLE instance
after it was successfully opened into a separate function.
This function will be reused in the following patches.

Free memory allocated by the server for all plugins,
with or without deinit() method.

            not tested by ABI check

plugin_audit.h and plugin_ftparser.h are now subject
for ABI check. plugin.h is now tested implicitly.

Also fixed broken ABI check cmake rules.

Handle combined instrument states of ENABLED and/or TIMED:

ENABLED TIMED
1 1 Aggregate stats, increment counter
1 0 Increment counter
0 1 Do nothing
0 0 Do nothing