Problem: wrong character set pointer was passed to my_strtoll10_mb2,
which led to DBUG_ASSERT failure in some cases.
@ mysql-test/r/func_encrypt_ucs2.result
@ mysql-test/t/func_encrypt_ucs2.test
@ mysql-test/r/ctype_ucs.result
@ mysql-test/t/ctype_ucs.test
Adding tests
@ sql/item_func.cc
"cs" initialization was wrong (res does not necessarily point to &str_value)
@ sql/item_strfunc.cc
Item_func_dec_encrypt::val_str() and Item_func_des_descrypt::val_str()
did not set character set for tmp_value (the returned value),
so the old value, which was previously copied from args[1]->val_str(),
was incorrectly returned with tmp_value.
