Revert our temporary fix for Bug#40360 Binlog related errors with binlog off

This bug was fixed in MySQL code.

Our fix went into r2944 and r2947, but this patch does not entirely revert
those revisions because we want to leave the test case that was introduced
and also r2944 itself reverted r2935 and r2936. So if we completely revert
r2944 and r2947 then we would loose the test and will restore r2935 and
r2936.

This resolves Issue#108 We should remove ib_bin_log_is_engaged() once mysql
add an equivallent, see Bug#40360