Bug#7834 Illegal mix of collations in IN operator
IN was the first function supporting
character set convertion.
agg_arg_charsets() was written afterwards,
which is more flexible.
Now IN just reuses this function.
Added a case for bug #6365.
item_cmpfunc.cc:
Fixed bug #6365 : Server crashed when list of values
in IN predicate contains NULL while the tested field is
of the character type and not of the default set;
e.g. when f in 'f IN (NULL,'aa') belongs to binary
character set, while the default character set is latin1.
Added more DBUG statements
Ensure that we are comparing end space with BINARY strings
Use 'any_db' instead of '' to mean any database. (For HANDLER command)
Only strip ' ' when comparing CHAR, not other space-like characters (like \t)
