Problem: Some system functions that could return different values on
master and slave were not marked unsafe. In particular:
 GET_LOCK
 IS_FREE_LOCK
 IS_USED_LOCK
 MASTER_POS_WAIT
 RELEASE_LOCK
 SLEEP
 SYSDATE
 VERSION
Fix: Mark these functions unsafe.


mysql-test/extra/rpl_tests/rpl_stm_000001.test:
  - The test does not work in mixed mode any more, since it tries to
    simulate an error in the sql thread in a query that uses get_lock.
    Since get_lock now causes the query to be logged in row format,
    the error didn't happen. Hence, we now force statement mode.
  - Warnings must be disabled when the unsafe query is issued.
  - Replaced some save_master_pos+connection slave+sync_with_master
    by sync_slave_with_master.
mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result:
  updated result file
mysql-test/suite/binlog/r/binlog_stm_row.result:
  updated result file
mysql-test/suite/binlog/r/binlog_unsafe.result:
  updated result file
mysql-test/suite/binlog/t/binlog_killed.test:
  binlog_killed only works in statement format now, since
  it switches to row mode in mixed mode.
mysql-test/suite/binlog/t/binlog_stm_mix_innodb_myisam.test:
  suppress warnings for unsafe statements
mysql-test/suite/binlog/t/binlog_stm_row.test:
  - Suppress warnings in test that causes warnings.
  - The test sets binlog format explicitly, so no need to execute it
    twice.
mysql-test/suite/binlog/t/binlog_unsafe.test:
  Added test for all unsafe system functions. This test also includes
  system functions that were unsafe prior to BUG#47995.
mysql-test/suite/rpl/r/rpl_err_ignoredtable.result:
  updated result file
mysql-test/suite/rpl/r/rpl_get_lock.result:
  updated result file
mysql-test/suite/rpl/r/rpl_nondeterministic_functions.result:
  new result file
mysql-test/suite/rpl/r/rpl_stm_000001.result:
  updated result file
mysql-test/suite/rpl/r/rpl_trigger.result:
  updated result file
mysql-test/suite/rpl/t/rpl_err_ignoredtable.test:
  - suppress warnings for unsafe statement
  - replaced save_master_pos+connection slave+sync_with_master
    with sync_slave_with_master
mysql-test/suite/rpl/t/rpl_get_lock.test:
  update test case that causes new warnings
mysql-test/suite/rpl/t/rpl_nondeterministic_functions.test:
  Added new test case for nondeterministic functions.
mysql-test/suite/rpl/t/rpl_trigger.test:
  update test case that causes new warnings
sql/item_create.cc:
  Marked some system functions unsafe.
sql/item_strfunc.cc:
  Clarified comment related to this bug.
sql/sql_yacc.yy:
  Marked sysdate unsafe.