Attempt to read the master-bin.state file always, even if the
binlog files (master-bin.index and master-bin.XXXXXX) have been
deleted.

This allows to easily preserve the binlog state when provisioning
a new server from a copy of an old one, without needing to copy
over the binlog files themselves.

mysql-test-run: *** ERROR: Could not find any of
/mariadb-5.5.34/sql/mysql_tzinfo_to_sql
/mariadb-5.5.34/build/client/mysql_tzinfo_to_sql
Fixed the directory list to search mysql_tzinfo_to_sql binary in.

The earlier pushed fix for the bug was incomplete. It did not remove
the main cause of the problem: the function remove_eq_conds()
removed always true multiple equalities from any conjunct, but did not
adjust the list of them stored in Item_cond_and::cond_equal.current_level.

Simplified the test case for the bug and moved it to another test file.

The fix triggered changes in EXPLAIN EXTENDED for some queries. 

MDEV-4725: Incorrect binlog state recovery if crash while writing event group

The binlog state was not recovered correctly if XA is not used (eg. InnoDB
disabled), or if server crashed in the middle of writing an event group to the
binlog.

With this patch, we ensure that recovery of binlog state is done even if we do
not do the full XA binlog recovery, and we ensure that we only recover fully
written event groups into the binlog state.

- Make log_slow_statement() always call delete_explain_query().

- Added testcase

Fixed.

- Don't pull out a table out of a semi-join if it is on the inner side of an outer join.
- Make join->sort_by_table= get_sort_by_table(...) call after const table detection 
  is done. That way, the value of join->sort_by_table will match the actual execution.
  Which will allow the code in setup_semijoin_dups_elimination() (search for 
  "Make sure that possible sorting of rows from the head table is not to be employed." 
  to see that "Using filesort" is going to be used together with Duplicate Elimination (
  and change it to Using temporary + Using filesort)

There were some places where insufficient locking between
parallel threads could cause invalid memory accesses and
possibly other grief.

This patch adds the missing locking, and moves the locking
into the struct rpl_binlog_state methods to make it easier
to see that proper locking is in place everywhere.

            -DINSTALL_SYSCONFDIR/-DDEFAULT_SYSCONFDIR specified

The reason for a bug is in support-files/CMakeLists.txt that tries to
install files in INSTALL_SYSCONF2DIR, without checking whether this
variable is actually defined. 

Normally INSTALL_SYSCONF2DIR is always defined if INSTALL_SYSCONFDIR is
defined, and support-files/CMakeLists.txt assumes that. But when one
specifies INSTALL_SYSCONFDIR manually on the command line, this
assumption might be broken.

(some patches reverted, test case added)

sort xtradb status variables

MDEV-5069: Server crashes in SEL_ARG::increment_use_count with index_merge+index_merge_sort_union, FORCE INDEX
- Don't call incr_refs() is the merged SEL_ARG* is NULL.

- make_join_readinfo() has the code that forces use of "Using temporary; 
  Using filesort" when join buffering is in use.
  That code didn't handle all cases, in particular it didn't hande the case 
  where ORDER BY originally has tables from multiple columns, but the 
  optimizer eventually figures out that doing filesort() on one table 
  will be sufficient.  Adjusted the code to handle that case.

Added test case for new system variable innodb_use_stacktrace and made sure that it can be used only on startup. Fixed compiler problems on solaris and other platforms that do not contain necessary headers and functions.

MDEV-5247: DB locked up at btr0cur.c line 568. Additional fixes to inconsistent usage of have_LRU_mutex and added additional debug assertions to guard incorrect usage of this mutex. Fixes issues found on additional testing and mysql test suite.

This bug was a consequence of the incorrect fix for bug mdev-5091.

Make sure to clear the temporary error before the retry.

Fix compiler error introduced on revision 3937, make sure that stackdump is compiled only on __linux__.

mysql_tzinfo_to_sql is not compiled under Windows in the pre-5.5 versions.
Do not set the MYSQL_TZINFO_TO_SQL variable in the version prior to 5.5
under Windows.

MDEV-5247: DB locked up at btr0cur.c line 568. There is inconsistent and non logical usage of have_LRU_mutex and incorrect value on ha_innodb.cc when buf_LRU_free_block is called. Additionally, for future long semaphore wait cases added a new configuration variable innodb_use_stacktrace. If this variable is true a signal handler for SIGUSR2 is installed when InnoDB server starts and when a long semaphore wait is detected at sync/sync0array.c we send SIGUSR2 signal to waiting thread and thread that has acuired RW-latch. For both threads a full stacktrace is produced as well as its is possible.