A couple of typos fixed.

sql/item.cc:
  A typo fixed in a comment, which is probably not valid any more
sql/sql_class.h:
  no such class Ttem_subselect.

sql/item.cc

@@ -1999,7 +1999,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
       }
       else if (tmp != not_found_field)
       {
-	ref= 0; // To prevent "delete *ref;" on ~Item_erf() of this item
+	ref= 0; // To prevent "delete *ref;" on ~Item_ref() of this item
 	Item_field* fld;
 	if (!((*reference)= fld= new Item_field(tmp)))
 	  return 1;

sql/sql_class.h

@@ -1264,8 +1264,6 @@ public:
   bool send_fields(List<Item> &list, uint flag) { return 0; };
   bool send_data(List<Item> &items)=0;
   bool send_eof() { return 0; };
-
-  friend class Ttem_subselect;
 };
 
 /* Single value subselect interface class */