- mdl.cc and mdl.h merged completely
- mysql_system_tables*.sql merged completely
- Fixed wrong merge of lock_tables
- Added some missing functions:
 - bool THD::notify_shared_lock()
 - Dynamic_array::pop, Dynamic_array::del
- Added MDL_context_owner to THD
- Added metadata_locks_hash_instances

  committer: Sergei Golubchik <sergii@pisem.net> 
    fix for a valgrind builds. 
    my_alloca() cannot have MY_THREAD_SPECIFIC, because can be used 
    outside of the THD context. 

MDEV-537 Make multi-column non-top level subqueries to be executed via index (index/unique subquery)
           instead of single_select_engine

This task changes the IN-EXISTS rewrite for multi-column subqueries
"(a, b) IN (select b, c ...)" to work in the same way as for
single-column subqueries "a IN (select b ...) with respect to the
injection of NULL-rejecting predicates.
 
More specifically, the method
Item_in_subselect::create_row_in_to_exists_cond()
adds Item_is_not_null_test and Item_func_trig_cond only if the left
IN operand can be NULL. Not having these predicates when not necessary,
makes it possible to rewrite the subquery into a "unique_subquery" or
"index_subquery" when there is a suitable index on the only
subquery table.

otherwise safemalloc and my_malloc_size_cb_func will use
current_thd before it's defined

MDEV-3997: Querying a Cassandra table on a server with query cache enabled is likely to cause problems
- Disable query cache for Cassandra tables.

my_alloca() cannot have MY_THREAD_SPECIFIC, because can be used
outside of the THD context.

when no ha_example.so is built

Add a wait for binlog checkpoint to avoid thread scheduling
giving different binlog order at random.

When CHANGE MASTER fails, it may or may not have already added
the Master_info * to the index. Implement logic that properly
handles removal and freeing in both cases.

to storage/cassandra/CMakeLists.txt

storage/cassandra/CMakeLists.txt:
  more thourough CHECK_CXX_SOURCE_COMPILES test, that checks whether
  boost::shared_ptr can work with --fno-rtti
  
  don't install anything in INSTALL_SYSCONFDIR, if the latter is unset

from MariaDB 10.0.
  
The bug in mdev-3948 was an instance of the problem fixed by Sergey's patch
in 10.0 - namely that the range optimizer could change table->[read | write]_set,
and not restore it.
  
revno: 3471
committer: Sergey Petrunya <psergey@askmonty.org>
branch nick: 10.0-serg-fix-imerge
timestamp: Sat 2012-11-03 12:24:36 +0400
message:
  # MDEV-3817: Wrong result with index_merge+index_merge_intersection, InnoDB table, join, AND and OR conditions
  Reconcile the fixes from:
  #
  # guilhem.bichot@oracle.com-20110805143029-ywrzuz15uzgontr0
  # Fix for BUG#12698916 - "JOIN QUERY GIVES WRONG RESULT AT 2ND EXEC. OR
  # AFTER FLUSH TABLES [-INT VS NULL]"
  #
  # guilhem.bichot@oracle.com-20111209150650-tzx3ldzxe1yfwji6
  # Fix for BUG#12912171 - ASSERTION FAILED: QUICK->HEAD->READ_SET == SAVE_READ_SET
  # and
  #
  and related fixes from: BUG#1006164, MDEV-376:
  
  Now, ROR-merged QUICK_RANGE_SELECT objects make no assumptions about the values
  of table->read_set and table->write_set.
  Each QUICK_ROR_SELECT has (and had before) its own column bitmap, but now, all 
  QUICK_ROR_SELECT's functions that care: reset(), init_ror_merged_scan(), and 
  get_next()  will set table->read_set when invoked and restore it back to what 
  it was before the call before they return.

  This allows to avoid the mess when somebody else modifies table->read_set for 
  some reason.

MDEV-3875 Wrong result (missing row) on a DISTINCT query with the same subquery in the SELECT list and GROUP BY

fix remove_dup_with_hash_index() and remove_dup_with_compare() to take NULLs into account