(recommit with the right Bug#)


mysql-test/r/sp.result:
  result file modified to reflect new test
mysql-test/t/sp.test:
  added test for the bug
sql/item.cc:
  protect Item_splocal value from modification by CONCAT() et al
sql/item.h:
  added a buffer to save Item_splocal string pointer
sql/sp_head.cc:
  don't employ reuse mechanism to save var into itself