Fixed a wrong result from mysqld--help.test.

This bug in the code of get_column_range_cardinality() could lead to
wrong estimates of number of records in ranges for non-nullable columns.  

Sampling of selectivity of LIKE predicate.

tables retrieved by range scans.

Added comments forgotten in the previous patch. 

mysql_options() with MYSQL_OPT_USE_THREAD_SPECIFIC_MEMORY

include/mysql.h:
  Added MYSQL_OPT_USE_THREAD_SPECIFIC_MEMORY
include/mysql.h.pp:
  Updated file
sql-common/client.c:
  Marked client memory as THREAD_SPECIFIC
sql/event_db_repository.cc:
  Fixed compiler warning
sql/slave.cc:
  Marked client memory as THREAD_SPECIFIC
storage/federatedx/federatedx_io_mysql.cc:
  Marked client memory as THREAD_SPECIFIC
storage/federatedx/ha_federatedx.cc:
  Marked client memory as THREAD_SPECIFIC
storage/sphinx/ha_sphinx.cc:
  Marked client memory as THREAD_SPECIFIC

sql/keycaches.cc:
  Added free_all_rpl_filters() to be able to free all filters at cleanup
sql/keycaches.h:
  Added prototype
sql/rpl_rli.cc:
  Fixed compiler warning
sql/slave.cc:
  Free all rpl_filters at cleanup
sql/sp.cc:
  Fixed compiler warning when not all struct elements was initialized
sql/sql_acl.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_events_waits.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_events_waits_summary.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_ews_global_by_event_name.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_file_instances.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_file_summary.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_performance_timers.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_setup_consumers.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_setup_instruments.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_setup_timers.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_sync_instances.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/perfschema/table_threads.cc:
  Fixed compiler warning when not all struct elements was initialized
storage/xtradb/os/os0file.c:
  Fixed compiler warning when not all struct elements was initialized

 - Fix embedded build

 - Backport disable of fallocate, it creates too short ibdata1
   when used with O_DIRECT on old kernels

 - Do not disable innodb during .deb install, we need it for
   mysql.rpl_slave_state table.

Users can set different repplication filter rules for each replication connection, in my.cnf or command line.
But the rules set online will not record in master.info, it means if users restart MySQL, these rules will lose.
So if users wantn't their replication filter rules lose, they should write the rules in my.cnf.

Users can set rules by 2 ways:
1. Online SET command, "SET connection_name.replication_filter_settings = rules;".
2. In my.cnf, "connection_name.replication_filter_settings = rules".

If no connection_name in my.cnf, this rule will apply for ALL replication connection.
If no connetion_name in SET statement, this rull will apply for default_connection_name.

The official Debian Wheezy MySQL packages have versions like 5.5.30+dfsg-xxx.
Such version is larger than 5.5.30-yyy, so apt prefers it.
So use instead 5.5.30+maria-yyy, which is larger and can be pulled in
automatically by apt.

Also included are a couple of fixes for test failures in buildbot.

Renamed the virtual method middle_point_pos for the class Field to
pos_in_interval.

Merge of 10.0-mdev26 feature tree into 10.0-base.

Global transaction ID is prepended to each event group in the binlog.

Slave connect can request to start from GTID position instead of specifying
file name/offset of master binlog. This facilitates easy switch to a new
master.

Slave GTID state is stored in a table mysql.rpl_slave_state, which can be
InnoDB to get crash-safe slave state.

GTID includes a replication domain ID, allowing to keep track of distinct
positions for each of multiple masters.

Fixed MDEV-4033 Unable to use slave's temporary directory /tmp - Can't create/write to file '/tmp/SQL_LOAD-' (Errcode: 17 "File exists")
- Cache value of check_temp_dir() to avoid race condition
- Set $rpl_server_count to avoid error in show_rpl_debug_info.inc

mysql-test/suite/multi_source/info_logs.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/multisource.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/relaylog_events.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/reset_slave.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/simple.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/skip_counter.test:
  Set $rpl_server_count
mysql-test/suite/multi_source/status_vars.test:
  Set $rpl_server_count
sql/slave.cc:
  Cache value of check_temp_dir() to avoid race condition

         Syntax modified to allow statements:
               ALTER TABLE ADD/DROP COLUMN
               ALTER TABLE ADD/DROP INDEX
               ALTER TABLE ADD/DROP FOREIGN KEY
               ALTER TABLE ADD/DROP PARTITION
               ALTER TABLE CHANGE COLUMN
               ALTER TABLE MODIFY COLUMN
               DROP INDEX
         to have IF (NOT) EXISTS options.
         Appropriate implementations added to mysql_alter_table().
      
      per-file comments:
        mysql-test/r/alter_table.result
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              test result updated.
        mysql-test/r/fulltext.result
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
        mysql-test/r/partition.result
              test result updated.
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
        mysql-test/t/alter_table.test
              tests added.
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
        mysql-test/t/fulltext.test
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              tests added.
        mysql-test/t/partition.test
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              tests added.
        sql/field.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              create_if_not_exists field added.
        sql/field.h
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              create_if_not_exists field added.
        sql/partition_info.h
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              has_unique_name made public.
        sql/sp_head.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
        sql/sql_class.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              create_if_not_exists inited.
        sql/sql_class.h
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              create_if_not_exists inited.
        sql/sql_lex.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              check_exists inited.
        sql/sql_lex.h
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              check_exists inited.
        sql/sql_parse.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
        check_exists inited.
        sql/sql_table.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              handle_if_exists_options() added.
              it's called in mysql_alter_table().
        sql/sql_trigger.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              check_exists instead of drop_if_exists.
        sql/sql_view.cc
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              check_exists instead of drop_if_exists.
        sql/sql_yacc.yy
      MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
              sintax modified.

    The patch contributed by Konstantin Osipov applied.
    Native comments:
      Implement multiple user-level locks per connection.

      GET_LOCK() function in MySQL allows a connection  to hold at most
      one user level lock. Taking a new lock automatically releases the
      old lock, if any.

      The limit of one lock per session existed since  early versions
      of MySQL didn't have a deadlock detector for SQL locks.
      MDL patches in MySQL 5.5 added a deadlock detector,
      so starting from 5.5 it became possible to take multiple locks
      in any order -- a deadlock, should it occur, would be detected
      and an error returned to the client which closed the wait chain.

      This is exactly what is done in this patch: ULLs are moved
      to use MDL subsystem.

This fixes that by default LOAD DATA INFILE will not generate the error:
"Multi-statement transaction required more than 'max_binlog_cache_size' bytes of storage..."


mysql-test/suite/sys_vars/r/max_binlog_cache_size_basic.result:
  Updated test case
mysql-test/suite/sys_vars/r/max_binlog_stmt_cache_size_basic.result:
  Updated test case
sql/sys_vars.cc:
  Increase default value of max_binlog_cache_size and max_binlog_stmt_cache_size to ulonglong_max.

The selectivity of a range degenerated into a point never should be set to 0.

(because only there it  makes any sense)