Use user's ip address when verifying privileges for SET ROLE (just like check_access() does)

If replication breaks in GTID mode, it is not trivial to determine the GTID of
the failing event group. This is a problem, as such GTID is needed eg. to
explicitly set @@gtid_slave_pos to skip to after that event group, or to
compare errors on different servers, etc.

Fix by ensuring that relevant slave errors logged to the error log include the
GTID of the event group containing the problem event.

This is MySQL Bug#59123. The message string stored in an INCIDENT event was
not zero-terminated. This caused any following checksum bytes (if enabled on
the master) to be output to the error log as trailing garbage when the message
was printed to the error log.

Backport the patch from MySQL 5.6:

  revno: 2876.228.200
  revision-id: zhenxing.he@sun.com-20110111051323-w2xnzvcjn46x6h6u
  committer: He Zhenxing <zhenxing.he@sun.com>
  timestamp: Tue 2011-01-11 13:13:23 +0800
  message:
    BUG#59123 rpl_stm_binlog_max_cache_size fails sporadically with found warnings

Also add a test case.

MySQL 5.6 implemented WL#344, which is about a MASTER_DELAY option to CHANGE
MASTER. But as part of this worklog, the format of the realy-log.info file was
changed. The new format is not understood by earlier versions, and nor by
MariaDB 10.0, so changing server to those versions would cause the slave to
abort with an error due to reading incorrect data out of relay-log.info.

Fix this by backporting from the WL#344 patch just the code that understands
the new relay-log.info format. We still write out the old format, and none of
the MASTER_DELAY feature is backported with this commit.

Stop spawning dummy threads on client library initialization

Let's revert the fix for Bug#24507.  To quote Monty from 2006:

"After 1/2 a year, when all glibc versions are updated, we can delete
this code."

Note: The upstream glibc bug was fixed in 2006.

Preserve CLIENT_REMEMBER_OPTIONS flag for compressed connections

Code cleanup: removed reference to CLIENT_REMEMBER_OPTIONS from server
code. This flag is ignored in MariaDB.

The INCIDENT_EVENT always caused slave error and abort, without checking
--slave-skip-errors.

Now, if error 1590, ER_SLAVE_INCIDENT is included in the --slave-skip-errors
list, incident events will be ignored.

This is a merge of this MySQL 5.6 patch:

revision-id: frazer@mysql.com-20110314170916-ypgin17otj3ucx95
committer: Frazer Clement <frazer@mysql.com>
timestamp: Mon 2011-03-14 17:09:16 +0000
message:
  Bug#11799671 NOT POSSIBLE TO SKIP INCIDENT ERRORS

Use single quotes for perl paths, in case of special symbols

Double-quoted string literals are subject to backslash and variable
substitution.

Fixed some compilation errors/warnings with ASan.

  Some variables weren't cleared properly so consequitive embedded server start/stop failed.
  Cleanups added. Also mysql_client_test.c extended to test that (taken from Mattias Johnson's patch)

When plugin=mysql_native_password (or mysql_old_password) take the password
from *either* password *or* authentication_string, whichever is set.
This makes no sense, but alas, that's what MySQL-5.6 does.

fix for ranges like "indexed_datetime OP time"
(test case is in the previous revision)

fix for ref like "indexed_time = datetime"

(prep for MDEV-6065)

The method JOIN_CACHE::init may fail (return 1) if some conditions on the
used join buffer is not satisfied. For example it fails if join_buffer_size
is greater than join_buffer_space_limit. The conditions should be checked
when running the EXPLAIN command for the query. That's why the method
JOIN_CACHE::init has to be called for EXPLAIN commands as well.

MDEV-4440 IF NOT EXISTS in multi-action ALTER does not work when the problem is created by a previous part of the ALTER.
        Loops added to the handle_if_exists_option() to check the
        CREATE/DROP lists for duplicates.

Part#1. 

table_cond_selectivity() should discount selectivity of table' 
conditions only when ity counts that selectivity to begin with. 

For non-ref-based access methods (ALL/range/index_merge/etc),
we start with sel=1.0 and hence do not need to discount any
selectivities.

- In table_cond_selectivity(), reset keyuse variable between the loops.