fix to functions as well.


mysql-test/r/sp.result:
  Modified test to trap yet another bug (now fixed).
mysql-test/t/sp.test:
  Modified test to trap yet another bug (now fixed).
sql/item.h:
  Another bugfix; need to override yet another method in Item_splocal.
sql/sp_head.cc:
  Completed previous initialization bug; now for FUNCTIONs. too.