bug fixes for my_vsnprintf

this also fixes a crash when plugin_init() uses ER() too early

(mysql-next-mr backport)

(instead of a C++ only thingy that was lost in a merge)

  function/ syntax
  glob(7) wildcards
  unit tests

per-file comments:
  mysql-test/r/mysql_upgrade.result
     result updated
  mysql-test/t/mysql_upgrade.test
     --skip-verbose option added to the call

   (backport)
   mysql_upgrade script accepts --upgrade-system-tables option,
   fixing only system tables in this case.

per-file comments:
  client/mysql_upgrade.c
WL#4991 mysql_upgrade --fix-privilege-tables
    --upgrade-system-tables option added.
   if it is set, the tool won't look for the mysqlcheck then
   run_mysqlcheck_fixnames() and run_mysqlcheck_upgrade won't be called.
  mysql-test/r/mysql_upgrade.result
WL#4991 mysql_upgrade --fix-privilege-tables
    test result added
  mysql-test/t/mysql_upgrade.test
WL#4991 mysql_upgrade --fix-privilege-tables
    test case added

Fixing locale name: en_US.UTF-8 -> en_US.utf8

Disabled rpl_cross_version (instead of setting it experimental).
Fixed outstanding warning fix in main.debug_sync.

result files.

Warnings affected:
 - WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED
 - ER_TOO_LONG_FIELD_COMMENT

Don't do character set autodetection when running
mysql from mysql_fix_privilege_tables.

Fixed problems:
- "mtr --mem mysql_locale_posix" could fail because of wrong temporary
  directory name: var/tmp/ -> $MYSQLTEST_VARDIR/tmp/
- "mtr federated_debug" could fail because of not compiled-in
   locale character set.  Always run mysqladmin with latin1.

rpl.rpl_heartbeat_basic and rpl.rpl_cross_version set as experimental.

Conflicts
=========

Text conflict in .bzr-mysql/default.conf
Text conflict in libmysqld/CMakeLists.txt
Text conflict in libmysqld/Makefile.am
Text conflict in mysql-test/collections/default.experimental
Text conflict in mysql-test/extra/rpl_tests/rpl_row_sp006.test
Text conflict in mysql-test/suite/binlog/r/binlog_tmp_table.result
Text conflict in mysql-test/suite/rpl/r/rpl_loaddata.result
Text conflict in mysql-test/suite/rpl/r/rpl_loaddata_fatal.result
Text conflict in mysql-test/suite/rpl/r/rpl_row_create_table.result
Text conflict in mysql-test/suite/rpl/r/rpl_row_sp006_InnoDB.result
Text conflict in mysql-test/suite/rpl/r/rpl_stm_log.result
Text conflict in mysql-test/suite/rpl_ndb/r/rpl_ndb_circular_simplex.result
Text conflict in mysql-test/suite/rpl_ndb/r/rpl_ndb_sp006.result
Text conflict in mysql-test/t/mysqlbinlog.test
Text conflict in sql/CMakeLists.txt
Text conflict in sql/Makefile.am
Text conflict in sql/log_event_old.cc
Text conflict in sql/rpl_rli.cc
Text conflict in sql/slave.cc
Text conflict in sql/sql_binlog.cc
Text conflict in sql/sql_lex.h
21 conflicts encountered.

NOTE
====
 mysql-5.1-rpl-merge has been made a mirror of mysql-next-mr:
 - "mysql-5.1-rpl-merge$ bzr pull ../mysql-next-mr"

 This is the first cset (merge/...) committed after pulling 
 from mysql-next-mr.

instead of making it experimental.