Simply testing if binary logging is enabled

In the MariaDB server most of the code uses different expressions to
test if binary logging should be done for the current query.

In many cases the current code does a lot of not needed work before
noticing that binary logging is not needed, which affects performance.

There is also a lot of different variables that affects if binary logging
should be used:

• (thd->variables.option_bits & OPTION_BIN_LOG)
• (thd->variables.option_bits & OPTION_BIN_TMP_LOG_OFF)
• WSREP(thd) && wsrep_emulate_bin_log && WSREP_PROVIDER_EXISTS_
• mysql_bin_log.is_open()
• xxx_binlog_local_stmt_filter()
• binlog_filter
• thd->variables.sql_log_bin

The goal is to move all states to a single variable (for performance,
simplicity and easier debugging). We should ignore all possible
extra work if binary logging is not needed for a particular query.

In most cases we can now use one the following functions to check if
we binary logging is needed. We need different version to be able
to shortcut code if binary logging is not enabled (with different
code paths if Galera is enabled or not).

• binlog_ready()
• binlog_ready_with_wsrep()
• binlog_ready_no_wsrep()
• binlog_ready_precheck()
• binlog_ready_later()

The state of binary logging is stored in thd->binlog_state.
There are a few bits that shows why binary logging is needed and
one bit for every different reasons for disabling binary logging.
By printing this variable (gdb prints all bits with there enum name)
one can exactly see why binary logging is not happening.

The initial bits are set in THD::THD() and THD::init() and verified in
THD::decide_logging_format().

In the current patch all testing of OPTION_BIN_LOG and most testing of
mysql_bin_log.is_open() is removed.
We should over time remove all testing of mysql_bin_log.is_open() from the
main code, except in binlog commit, as the value can change 'anytime' if
binlog rotation fails, which is very likely to result in crashes.
(The patch fixes some of these).