Fix for a bug with ROW(..) <=> ROW(...)

mysql-test/r/row.result

@@ -159,3 +159,9 @@ a	MAX(b)	(1, MAX(b)) = (1, 4)
 1	4	1
 10	43	0
 drop table t1;
+SELECT ROW(2,10) <=> ROW(3,4);
+ROW(2,10) <=> ROW(3,4)
+0
+SELECT ROW(NULL,10) <=> ROW(3,NULL);
+ROW(NULL,10) <=> ROW(3,NULL)
+0

mysql-test/t/row.test

@@ -79,3 +79,5 @@ insert into t1 values (10, 43);
 insert into t1 values (1, 4);
 select a, MAX(b), (1, MAX(b)) = (1, 4) from t1 group by a;
 drop table t1;
+SELECT ROW(2,10) <=> ROW(3,4);
+SELECT ROW(NULL,10) <=> ROW(3,NULL);

sql/item_cmpfunc.cc

@@ -266,8 +266,8 @@ int Arg_comparator::compare_e_row()
   uint n= (*a)->cols();
   for (uint i= 0; i<n; i++)
   {
-    if ((res= comparators[i].compare()))
-      return 1;
+    if ((res= !comparators[i].compare()))
+      return 0;
   }
   return 1;
 }
@@ -352,7 +352,6 @@ void Item_func_equal::fix_length_and_dec()
 {
   Item_bool_func2::fix_length_and_dec();
   maybe_null=null_value=0;
-  set_cmp_func();
 }
 
 longlong Item_func_equal::val_int()