mysql-test/r/sp.result:
  New test (of more call levels).
mysql-test/t/sp.test:
  New test (of more call levels).
sql/mysql_priv.h:
  SPs wants to init lex only.
sql/sp.cc:
  Restore lex pointer (and fixed memory leak).
sql/sp_head.cc:
  lex is now a pointer, so reset things the right way.
sql/sp_head.h:
  lex is now a pointer.
sql/sql_lex.h:
  SPs wants to init lex only.
sql/sql_parse.cc:
  SPs wants to init lex only.
sql/sql_prepare.cc:
  Restore lex pointer.