away.
During optimization stage the WHERE conditions can be changed or even
be removed at all if they know for sure to be true of false. Thus they aren't
showed in the EXPLAIN EXTENDED which prints conditions after optimization.
Now if all elements of an Item_cond were removed this Item_cond is substituted
for an Item_int with the int value of the Item_cond.
If there were conditions that were totally optimized away then values of the
saved cond_value and having_value will be printed instead.
There were two distict bugs: parse error was returned for valid
statement and that error wasn't reported to the client.
The fix ensures that EXPLAIN SELECT..INTO is accepted by parser and any
other parse error will be reported to the client.
